diff --git a/.travis.yml b/.travis.yml
index 278c18bd260..dec7987e178 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -27,8 +27,6 @@ matrix:
          - ./mach build -d --verbose
          - ./mach test-unit
          - ./mach clean
-         - ./mach build-geckolib
-         - ./mach test-stylo
          - bash etc/ci/lockfile_changed.sh
       cache:
         directories:
diff --git a/components/gfx/font.rs b/components/gfx/font.rs
index 09578168ea7..2cf92e6a328 100644
--- a/components/gfx/font.rs
+++ b/components/gfx/font.rs
@@ -19,7 +19,7 @@ use std::rc::Rc;
 use std::str;
 use std::sync::Arc;
 use std::sync::atomic::{ATOMIC_USIZE_INIT, AtomicUsize, Ordering};
-use style::computed_values::{font_stretch, font_variant_caps, font_weight};
+use style::computed_values::{font_stretch, font_style, font_variant_caps, font_weight};
 use style::properties::style_structs::Font as FontStyleStruct;
 use style::values::computed::font::SingleFontFamily;
 use text::Shaper;
@@ -47,18 +47,24 @@ static TEXT_SHAPING_PERFORMANCE_COUNTER: AtomicUsize = ATOMIC_USIZE_INIT;
 // resources needed by the graphics layer to draw glyphs.
 
 pub trait FontHandleMethods: Sized {
-    fn new_from_template(fctx: &FontContextHandle, template: Arc<FontTemplateData>, pt_size: Option<Au>)
-                    -> Result<Self, ()>;
+    fn new_from_template(
+        fctx: &FontContextHandle,
+        template: Arc<FontTemplateData>,
+        pt_size: Option<Au>,
+    ) -> Result<Self, ()>;
+
     fn template(&self) -> Arc<FontTemplateData>;
     fn family_name(&self) -> String;
     fn face_name(&self) -> Option<String>;
-    fn is_italic(&self) -> bool;
+
+    fn style(&self) -> font_style::T;
     fn boldness(&self) -> font_weight::T;
     fn stretchiness(&self) -> font_stretch::T;
 
     fn glyph_index(&self, codepoint: char) -> Option<GlyphId>;
     fn glyph_h_advance(&self, GlyphId) -> Option<FractionalPixel>;
     fn glyph_h_kerning(&self, glyph0: GlyphId, glyph1: GlyphId) -> FractionalPixel;
+
     /// Can this font do basic horizontal LTR shaping without Harfbuzz?
     fn can_do_fast_shaping(&self) -> bool;
     fn metrics(&self) -> FontMetrics;
diff --git a/components/gfx/font_cache_thread.rs b/components/gfx/font_cache_thread.rs
index fdb48e519fe..39375191ae1 100644
--- a/components/gfx/font_cache_thread.rs
+++ b/components/gfx/font_cache_thread.rs
@@ -18,14 +18,11 @@ use platform::font_list::system_default_family;
 use platform::font_template::FontTemplateData;
 use servo_atoms::Atom;
 use servo_url::ServoUrl;
+use std::{fmt, f32, mem, thread};
 use std::borrow::ToOwned;
 use std::collections::HashMap;
-use std::fmt;
-use std::mem;
 use std::ops::Deref;
 use std::sync::{Arc, Mutex};
-use std::thread;
-use std::u32;
 use style::font_face::{EffectiveSources, Source};
 use style::values::computed::font::{SingleFontFamily, FamilyName};
 use webrender_api;
@@ -63,7 +60,7 @@ impl FontTemplates {
 
         // We didn't find an exact match. Do more expensive fuzzy matching.
         // TODO(#190): Do a better job.
-        let (mut best_template_data, mut best_distance) = (None, u32::MAX);
+        let (mut best_template_data, mut best_distance) = (None, f32::MAX);
         for template in &mut self.templates {
             if let Some((template_data, distance)) =
                     template.data_for_approximate_descriptor(fctx, desc) {
diff --git a/components/gfx/font_template.rs b/components/gfx/font_template.rs
index 239bfcdd8c9..13c531f4d43 100644
--- a/components/gfx/font_template.rs
+++ b/components/gfx/font_template.rs
@@ -10,7 +10,6 @@ use servo_atoms::Atom;
 use std::fmt::{Debug, Error, Formatter};
 use std::io::Error as IoError;
 use std::sync::{Arc, Weak};
-use std::u32;
 use style::computed_values::font_stretch::T as FontStretch;
 use style::computed_values::font_style::T as FontStyle;
 use style::properties::style_structs::Font as FontStyleStruct;
@@ -20,21 +19,35 @@ use style::values::computed::font::FontWeight;
 /// to be expanded or refactored when we support more of the font styling parameters.
 ///
 /// NB: If you change this, you will need to update `style::properties::compute_font_hash()`.
-#[derive(Clone, Copy, Debug, Deserialize, Eq, Hash, Serialize)]
+#[derive(Clone, Copy, Debug, Deserialize, PartialEq, Serialize)]
 pub struct FontTemplateDescriptor {
     pub weight: FontWeight,
     pub stretch: FontStretch,
-    pub italic: bool,
+    pub style: FontStyle,
 }
 
+fn style_to_number(s: &FontStyle) -> f32 {
+    use style::values::generics::font::FontStyle as GenericFontStyle;
+
+    match *s {
+        GenericFontStyle::Normal => 0.,
+        GenericFontStyle::Italic => FontStyle::default_angle().0.degrees(),
+        GenericFontStyle::Oblique(ref angle) => angle.0.degrees(),
+    }
+}
+
+
 impl FontTemplateDescriptor {
     #[inline]
-    pub fn new(weight: FontWeight, stretch: FontStretch, italic: bool)
-               -> FontTemplateDescriptor {
-        FontTemplateDescriptor {
-            weight: weight,
-            stretch: stretch,
-            italic: italic,
+    pub fn new(
+        weight: FontWeight,
+        stretch: FontStretch,
+        style: FontStyle,
+    ) -> Self {
+        Self {
+            weight,
+            stretch,
+            style,
         }
     }
 
@@ -46,30 +59,15 @@ impl FontTemplateDescriptor {
     ///
     /// The policy is to care most about differences in italicness, then weight, then stretch
     #[inline]
-    fn distance_from(&self, other: &FontTemplateDescriptor) -> u32 {
-        let italic_part = if self.italic == other.italic { 0 } else { 1000 };
+    fn distance_from(&self, other: &FontTemplateDescriptor) -> f32 {
+        // 0 <= style_part <= 180, since font-style obliqueness should be
+        // between -90 and +90deg.
+        let style_part = (style_to_number(&self.style) - style_to_number(&other.style)).abs();
         // 0 <= weightPart <= 800
-        let weight_part = ((self.weight.0 as i16) - (other.weight.0 as i16)).abs() as u32;
+        let weight_part = (self.weight.0 - other.weight.0).abs();
         // 0 <= stretchPart <= 8
-        let stretch_part = (self.stretch_number() - other.stretch_number()).abs() as u32;
-        italic_part + weight_part + stretch_part
-    }
-
-    /// Returns a number between 1 and 9 for the stretch property.
-    /// 1 is ultra_condensed, 5 is normal, and 9 is ultra_expanded
-    #[inline]
-    fn stretch_number(&self) -> i32 {
-        match self.stretch {
-            FontStretch::UltraCondensed => 1,
-            FontStretch::ExtraCondensed => 2,
-            FontStretch::Condensed      => 3,
-            FontStretch::SemiCondensed  => 4,
-            FontStretch::Normal         => 5,
-            FontStretch::SemiExpanded   => 6,
-            FontStretch::Expanded       => 7,
-            FontStretch::ExtraExpanded  => 8,
-            FontStretch::UltraExpanded  => 9,
-        }
+        let stretch_part = ((self.stretch.0).0 - (other.stretch.0).0).abs();
+        style_part + weight_part + stretch_part
     }
 }
 
@@ -78,17 +76,11 @@ impl<'a> From<&'a FontStyleStruct> for FontTemplateDescriptor {
         FontTemplateDescriptor {
             weight: style.font_weight,
             stretch: style.font_stretch,
-            italic: style.font_style == FontStyle::Italic || style.font_style == FontStyle::Oblique,
+            style: style.font_style,
         }
     }
 }
 
-impl PartialEq for FontTemplateDescriptor {
-    fn eq(&self, other: &FontTemplateDescriptor) -> bool {
-        self.weight == other.weight && self.stretch == other.stretch && self.italic == other.italic
-    }
-}
-
 /// This describes all the information needed to create
 /// font instance handles. It contains a unique
 /// FontTemplateData structure that is platform specific.
@@ -173,10 +165,11 @@ impl FontTemplate {
 
     /// Returns the font data along with the distance between this font's descriptor and the given
     /// descriptor, if the font can be loaded.
-    pub fn data_for_approximate_descriptor(&mut self,
-                                           font_context: &FontContextHandle,
-                                           requested_descriptor: &FontTemplateDescriptor)
-                                           -> Option<(Arc<FontTemplateData>, u32)> {
+    pub fn data_for_approximate_descriptor(
+        &mut self,
+        font_context: &FontContextHandle,
+        requested_descriptor: &FontTemplateDescriptor,
+    ) -> Option<(Arc<FontTemplateData>, f32)> {
         self.descriptor(&font_context).and_then(|descriptor| {
             self.data().ok().map(|data| {
                 (data, descriptor.distance_from(requested_descriptor))
@@ -195,9 +188,11 @@ impl FontTemplate {
                                                                                   None);
         self.is_valid = handle.is_ok();
         let handle = handle?;
-        self.descriptor = Some(FontTemplateDescriptor::new(handle.boldness(),
-                                                           handle.stretchiness(),
-                                                           handle.is_italic()));
+        self.descriptor = Some(FontTemplateDescriptor::new(
+            handle.boldness(),
+            handle.stretchiness(),
+            handle.style(),
+        ));
         Ok(())
     }
 
diff --git a/components/gfx/platform/freetype/font.rs b/components/gfx/platform/freetype/font.rs
index 940563d7d29..506d6be2117 100644
--- a/components/gfx/platform/freetype/font.rs
+++ b/components/gfx/platform/freetype/font.rs
@@ -24,6 +24,7 @@ use std::os::raw::{c_char, c_long};
 use std::sync::Arc;
 use style::computed_values::font_stretch::T as FontStretch;
 use style::computed_values::font_weight::T as FontWeight;
+use style::values::computed::font::FontStyle;
 use super::c_str_to_string;
 use text::glyph::GlyphId;
 use text::util::fixed_to_float;
@@ -149,43 +150,44 @@ impl FontHandleMethods for FontHandle {
         }
     }
 
-    fn is_italic(&self) -> bool {
-        unsafe { (*self.face).style_flags & FT_STYLE_FLAG_ITALIC as c_long != 0 }
+    fn style(&self) -> FontStyle {
+        use style::values::generics::font::FontStyle::*;
+        if unsafe { (*self.face).style_flags & FT_STYLE_FLAG_ITALIC as c_long != 0 } {
+            Italic
+        } else {
+            Normal
+        }
     }
 
     fn boldness(&self) -> FontWeight {
-        if let Some(os2) = self.os2_table() {
-            let weight = os2.us_weight_class as i32;
-
-            if weight < 10 {
-                FontWeight::from_int(weight * 100).unwrap()
-            } else if weight >= 100 && weight < 1000 {
-                FontWeight::from_int(weight / 100 * 100).unwrap()
-            } else {
-                FontWeight::normal()
-            }
-        } else {
-            FontWeight::normal()
-        }
+        let os2 = match self.os2_table() {
+            None => return FontWeight::normal(),
+            Some(os2) => os2,
+        };
+        let weight = os2.us_weight_class as f32;
+        FontWeight(weight.max(1.).min(1000.))
     }
 
     fn stretchiness(&self) -> FontStretch {
-        if let Some(os2) = self.os2_table() {
+        use style::values::generics::NonNegative;
+        use style::values::specified::font::FontStretchKeyword;
+        let percentage = if let Some(os2) = self.os2_table() {
             match os2.us_width_class {
-                1 => FontStretch::UltraCondensed,
-                2 => FontStretch::ExtraCondensed,
-                3 => FontStretch::Condensed,
-                4 => FontStretch::SemiCondensed,
-                5 => FontStretch::Normal,
-                6 => FontStretch::SemiExpanded,
-                7 => FontStretch::Expanded,
-                8 => FontStretch::ExtraExpanded,
-                9 => FontStretch::UltraExpanded,
-                _ => FontStretch::Normal
+                1 => FontStretchKeyword::UltraCondensed,
+                2 => FontStretchKeyword::ExtraCondensed,
+                3 => FontStretchKeyword::Condensed,
+                4 => FontStretchKeyword::SemiCondensed,
+                5 => FontStretchKeyword::Normal,
+                6 => FontStretchKeyword::SemiExpanded,
+                7 => FontStretchKeyword::Expanded,
+                8 => FontStretchKeyword::ExtraExpanded,
+                9 => FontStretchKeyword::UltraExpanded,
+                _ => FontStretchKeyword::Normal
             }
         } else {
-            FontStretch::Normal
-        }
+            FontStretchKeyword::Normal
+        }.compute();
+        NonNegative(percentage)
     }
 
     fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {
diff --git a/components/gfx/platform/macos/font.rs b/components/gfx/platform/macos/font.rs
index ca719ddf5b7..5eacf92ffd6 100644
--- a/components/gfx/platform/macos/font.rs
+++ b/components/gfx/platform/macos/font.rs
@@ -22,8 +22,7 @@ use servo_atoms::Atom;
 use std::{fmt, ptr};
 use std::ops::Range;
 use std::sync::Arc;
-use style::computed_values::font_stretch::T as FontStretch;
-use style::computed_values::font_weight::T as FontWeight;
+use style::values::computed::font::{FontStretch, FontStyle, FontWeight};
 use text::glyph::GlyphId;
 
 const KERN_PAIR_LEN: usize = 6;
@@ -204,34 +203,33 @@ impl FontHandleMethods for FontHandle {
         Some(self.ctfont.face_name())
     }
 
-    fn is_italic(&self) -> bool {
-        self.ctfont.symbolic_traits().is_italic()
+    fn style(&self) -> FontStyle {
+        use style::values::generics::font::FontStyle::*;
+        if self.ctfont.symbolic_traits().is_italic() {
+            Italic
+        } else {
+            Normal
+        }
     }
 
     fn boldness(&self) -> FontWeight {
         let normalized = self.ctfont.all_traits().normalized_weight();  // [-1.0, 1.0]
+        // TODO(emilio): It may make sense to make this range [.01, 10.0], to
+        // align with css-fonts-4's range of [1, 1000].
         let normalized = if normalized <= 0.0 {
             4.0 + normalized * 3.0  // [1.0, 4.0]
         } else {
             4.0 + normalized * 5.0  // [4.0, 9.0]
         }; // [1.0, 9.0], centered on 4.0
-        FontWeight::from_int(normalized.round() as i32 * 100).unwrap()
+        FontWeight(normalized as f32 * 100.)
     }
 
     fn stretchiness(&self) -> FontStretch {
+        use style::values::computed::Percentage;
+        use style::values::generics::NonNegative;
+
         let normalized = self.ctfont.all_traits().normalized_width();  // [-1.0, 1.0]
-        let normalized = (normalized + 1.0) / 2.0 * 9.0;  // [0.0, 9.0]
-        match normalized {
-            v if v < 1.0 => FontStretch::UltraCondensed,
-            v if v < 2.0 => FontStretch::ExtraCondensed,
-            v if v < 3.0 => FontStretch::Condensed,
-            v if v < 4.0 => FontStretch::SemiCondensed,
-            v if v < 5.0 => FontStretch::Normal,
-            v if v < 6.0 => FontStretch::SemiExpanded,
-            v if v < 7.0 => FontStretch::Expanded,
-            v if v < 8.0 => FontStretch::ExtraExpanded,
-            _ => FontStretch::UltraExpanded,
-        }
+        NonNegative(Percentage(normalized as f32 + 1.0))
     }
 
     fn glyph_index(&self, codepoint: char) -> Option<GlyphId> {
diff --git a/components/gfx/platform/windows/font.rs b/components/gfx/platform/windows/font.rs
index 12df6d547d2..ed94d0fc5a2 100644
--- a/components/gfx/platform/windows/font.rs
+++ b/components/gfx/platform/windows/font.rs
@@ -19,6 +19,10 @@ use servo_atoms::Atom;
 use std::sync::Arc;
 use style::computed_values::font_stretch::T as StyleFontStretch;
 use style::computed_values::font_weight::T as StyleFontWeight;
+use style::values::computed::font::FontStyle as StyleFontStyle;
+use style::values::generics::NonNegative;
+use style::values::generics::font::FontStyle as GenericFontStyle;
+use style::values::specified::font::FontStretchKeyword;
 use text::glyph::GlyphId;
 use truetype;
 
@@ -98,7 +102,7 @@ struct FontInfo {
     face_name: String,
     weight: StyleFontWeight,
     stretch: StyleFontStretch,
-    style: FontStyle,
+    style: StyleFontStyle,
 }
 
 impl FontInfo {
@@ -157,75 +161,76 @@ impl FontInfo {
             },
         };
 
-        let weight =
-            StyleFontWeight::from_int(
-                min(9, max(1, weight_val as i32 / 100)) * 100
-            ).unwrap();
+        let weight = StyleFontWeight(weight_val as f32);
 
-        let stretch = match min(9, max(1, width_val)) {
-            1 => StyleFontStretch::UltraCondensed,
-            2 => StyleFontStretch::ExtraCondensed,
-            3 => StyleFontStretch::Condensed,
-            4 => StyleFontStretch::SemiCondensed,
-            5 => StyleFontStretch::Normal,
-            6 => StyleFontStretch::SemiExpanded,
-            7 => StyleFontStretch::Expanded,
-            8 => StyleFontStretch::ExtraExpanded,
-            9 => StyleFontStretch::UltraExpanded,
+        let stretch = NonNegative(match min(9, max(1, width_val)) {
+            1 => FontStretchKeyword::UltraCondensed,
+            2 => FontStretchKeyword::ExtraCondensed,
+            3 => FontStretchKeyword::Condensed,
+            4 => FontStretchKeyword::SemiCondensed,
+            5 => FontStretchKeyword::Normal,
+            6 => FontStretchKeyword::SemiExpanded,
+            7 => FontStretchKeyword::Expanded,
+            8 => FontStretchKeyword::ExtraExpanded,
+            9 => FontStretchKeyword::UltraExpanded,
             _ => return Err(()),
-        };
+        }.compute());
 
         let style = if italic_bool {
-            FontStyle::Italic
+            GenericFontStyle::Italic
         } else {
-            FontStyle::Normal
+            GenericFontStyle::Normal
         };
 
         Ok(FontInfo {
             family_name: family,
             face_name: face,
-            weight: weight,
-            stretch: stretch,
-            style: style,
+            weight,
+            stretch,
+            style,
         })
     }
 
     fn new_from_font(font: &Font) -> Result<FontInfo, ()> {
-        let style = font.style();
-        let weight = StyleFontWeight(match font.weight() {
-            FontWeight::Thin => 100,
-            FontWeight::ExtraLight => 200,
-            FontWeight::Light => 300,
-            // slightly grayer gray
-            FontWeight::SemiLight => 300,
-            FontWeight::Regular => 400,
-            FontWeight::Medium => 500,
-            FontWeight::SemiBold => 600,
-            FontWeight::Bold => 700,
-            FontWeight::ExtraBold => 800,
-            FontWeight::Black => 900,
-            // slightly blacker black
-            FontWeight::ExtraBlack => 900,
-        });
-        let stretch = match font.stretch() {
-            FontStretch::Undefined => StyleFontStretch::Normal,
-            FontStretch::UltraCondensed => StyleFontStretch::UltraCondensed,
-            FontStretch::ExtraCondensed => StyleFontStretch::ExtraCondensed,
-            FontStretch::Condensed => StyleFontStretch::Condensed,
-            FontStretch::SemiCondensed => StyleFontStretch::SemiCondensed,
-            FontStretch::Normal => StyleFontStretch::Normal,
-            FontStretch::SemiExpanded => StyleFontStretch::SemiExpanded,
-            FontStretch::Expanded => StyleFontStretch::Expanded,
-            FontStretch::ExtraExpanded => StyleFontStretch::ExtraExpanded,
-            FontStretch::UltraExpanded => StyleFontStretch::UltraExpanded,
+        let style = match font.style() {
+            FontStyle::Normal => GenericFontStyle::Normal,
+            FontStyle::Oblique => GenericFontStyle::Oblique(StyleFontStyle::default_angle()),
+            FontStyle::Italic => GenericFontStyle::Italic,
         };
+        let weight = StyleFontWeight(match font.weight() {
+            FontWeight::Thin => 100.,
+            FontWeight::ExtraLight => 200.,
+            FontWeight::Light => 300.,
+            // slightly grayer gray
+            FontWeight::SemiLight => 300.,
+            FontWeight::Regular => 400.,
+            FontWeight::Medium => 500.,
+            FontWeight::SemiBold => 600.,
+            FontWeight::Bold => 700.,
+            FontWeight::ExtraBold => 800.,
+            FontWeight::Black => 900.,
+            // slightly blacker black
+            FontWeight::ExtraBlack => 1000.,
+        });
+        let stretch = NonNegative(match font.stretch() {
+            FontStretch::Undefined => FontStretchKeyword::Normal,
+            FontStretch::UltraCondensed => FontStretchKeyword::UltraCondensed,
+            FontStretch::ExtraCondensed => FontStretchKeyword::ExtraCondensed,
+            FontStretch::Condensed => FontStretchKeyword::Condensed,
+            FontStretch::SemiCondensed => FontStretchKeyword::SemiCondensed,
+            FontStretch::Normal => FontStretchKeyword::Normal,
+            FontStretch::SemiExpanded => FontStretchKeyword::SemiExpanded,
+            FontStretch::Expanded => FontStretchKeyword::Expanded,
+            FontStretch::ExtraExpanded => FontStretchKeyword::ExtraExpanded,
+            FontStretch::UltraExpanded => FontStretchKeyword::UltraExpanded,
+        }.compute());
 
         Ok(FontInfo {
             family_name: font.family_name(),
             face_name: font.face_name(),
-            style: style,
-            weight: weight,
-            stretch: stretch,
+            style,
+            weight,
+            stretch,
         })
     }
 }
@@ -297,11 +302,8 @@ impl FontHandleMethods for FontHandle {
         Some(self.info.face_name.clone())
     }
 
-    fn is_italic(&self) -> bool {
-        match self.info.style {
-            FontStyle::Normal => false,
-            FontStyle::Oblique | FontStyle::Italic => true,
-        }
+    fn style(&self) -> StyleFontStyle {
+        self.info.style
     }
 
     fn boldness(&self) -> StyleFontWeight {
diff --git a/components/gfx/tests/font_context.rs b/components/gfx/tests/font_context.rs
index f7fef58a5c2..c918ef86e90 100644
--- a/components/gfx/tests/font_context.rs
+++ b/components/gfx/tests/font_context.rs
@@ -22,12 +22,13 @@ use std::fs::File;
 use std::io::prelude::*;
 use std::path::PathBuf;
 use std::rc::Rc;
-use style::properties::longhands::font_stretch::computed_value::T as FontStretch;
-use style::properties::longhands::font_style::computed_value::T as FontStyle;
 use style::properties::longhands::font_variant_caps::computed_value::T as FontVariantCaps;
 use style::properties::style_structs::Font as FontStyleStruct;
+use style::values::computed::Percentage;
 use style::values::computed::font::{FamilyName, FamilyNameSyntax, FontFamily, FontFamilyList, FontSize};
 use style::values::computed::font::{FontWeight, SingleFontFamily};
+use style::values::generics::NonNegative;
+use style::values::generics::font::FontStyle;
 
 struct TestFontSource {
     handle: FontContextHandle,
@@ -108,7 +109,7 @@ fn style() -> FontStyleStruct {
         font_variant_caps: FontVariantCaps::Normal,
         font_weight: FontWeight::normal(),
         font_size: FontSize::medium(),
-        font_stretch: FontStretch::Normal,
+        font_stretch: NonNegative(Percentage(1.)),
         hash: 0,
     };
     style.compute_font_hash();
diff --git a/components/gfx/tests/font_template.rs b/components/gfx/tests/font_template.rs
index 4b513d9f0c4..af31d8f229d 100644
--- a/components/gfx/tests/font_template.rs
+++ b/components/gfx/tests/font_template.rs
@@ -16,8 +16,10 @@ fn test_font_template_descriptor() {
     use std::fs::File;
     use std::io::prelude::*;
     use std::path::PathBuf;
-    use style::computed_values::font_stretch::T as FontStretch;
+    use style::values::computed::Percentage;
     use style::values::computed::font::FontWeight;
+    use style::values::generics::NonNegative;
+    use style::values::generics::font::FontStyle;
 
     fn descriptor(filename: &str) -> FontTemplateDescriptor {
         let mut path: PathBuf = [
@@ -43,25 +45,25 @@ fn test_font_template_descriptor() {
 
     assert_eq!(descriptor("DejaVuSans"), FontTemplateDescriptor {
         weight: FontWeight::normal(),
-        stretch: FontStretch::Normal,
-        italic: false,
+        stretch: NonNegative(Percentage(1.)),
+        style: FontStyle::Normal,
     });
 
     assert_eq!(descriptor("DejaVuSans-Bold"), FontTemplateDescriptor {
         weight: FontWeight::bold(),
-        stretch: FontStretch::Normal,
-        italic: false,
+        stretch: NonNegative(Percentage(1.)),
+        style: FontStyle::Normal,
     });
 
     assert_eq!(descriptor("DejaVuSans-Oblique"), FontTemplateDescriptor {
         weight: FontWeight::normal(),
-        stretch: FontStretch::Normal,
-        italic: true,
+        stretch: NonNegative(Percentage(1.)),
+        style: FontStyle::Italic,
     });
 
     assert_eq!(descriptor("DejaVuSansCondensed-BoldOblique"), FontTemplateDescriptor {
         weight: FontWeight::bold(),
-        stretch: FontStretch::SemiCondensed,
-        italic: true,
+        stretch: NonNegative(Percentage(0.875)),
+        style: FontStyle::Italic,
     });
 }
diff --git a/components/layout/multicol.rs b/components/layout/multicol.rs
index 3659d50e219..487a878c08b 100644
--- a/components/layout/multicol.rs
+++ b/components/layout/multicol.rs
@@ -104,13 +104,13 @@ impl Flow for MulticolFlow {
             self.block_flow.fragment.border_box.size.inline - padding_and_borders;
         let column_width;
         {
-            let column_style = self.block_flow.fragment.style.get_column();
-
-            let column_gap = match column_style.column_gap {
+            let style = &self.block_flow.fragment.style;
+            let column_gap = match style.get_position().column_gap {
                 Either::First(len) => len.0.to_pixel_length(content_inline_size).into(),
                 Either::Second(_normal) => self.block_flow.fragment.style.get_font().font_size.size(),
             };
 
+            let column_style = style.get_column();
             let mut column_count;
             if let Either::First(column_width) = column_style.column_width {
                 let column_width = Au::from(column_width);
diff --git a/components/style/applicable_declarations.rs b/components/style/applicable_declarations.rs
index ab7c47307d7..d4674fa1bc7 100644
--- a/components/style/applicable_declarations.rs
+++ b/components/style/applicable_declarations.rs
@@ -5,12 +5,11 @@
 //! Applicable declarations management.
 
 use properties::PropertyDeclarationBlock;
-use rule_tree::{CascadeLevel, StyleSource};
+use rule_tree::{CascadeLevel, ShadowCascadeOrder, StyleSource};
 use servo_arc::Arc;
 use shared_lock::Locked;
 use smallvec::SmallVec;
 use std::fmt::{self, Debug};
-use std::mem;
 
 /// List of applicable declarations. This is a transient structure that shuttles
 /// declarations between selector matching and inserting into the rule tree, and
@@ -25,45 +24,67 @@ pub type ApplicableDeclarationList = SmallVec<[ApplicableDeclarationBlock; 16]>;
 /// That's a limit that could be reached in realistic webpages, so we use
 /// 24 bits and enforce defined behavior in the overflow case.
 ///
-/// Note that the value of 24 is also hard-coded into the level() accessor,
-/// which does a byte-aligned load of the 4th byte. If you change this value
-/// you'll need to change that as well.
-///
 /// [1] https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/css/
 ///     RuleSet.h?l=128&rcl=90140ab80b84d0f889abc253410f44ed54ae04f3
+const SOURCE_ORDER_SHIFT: usize = 0;
 const SOURCE_ORDER_BITS: usize = 24;
-const SOURCE_ORDER_MASK: u32 = (1 << SOURCE_ORDER_BITS) - 1;
-const SOURCE_ORDER_MAX: u32 = SOURCE_ORDER_MASK;
+const SOURCE_ORDER_MAX: u32 = (1 << SOURCE_ORDER_BITS) - 1;
+const SOURCE_ORDER_MASK: u32 = SOURCE_ORDER_MAX << SOURCE_ORDER_SHIFT;
 
-/// Stores the source order of a block and the cascade level it belongs to.
+/// We store up-to-15 shadow order levels.
+///
+/// You'd need an element slotted across 16 components with ::slotted rules to
+/// trigger this as of this writing, which looks... Unlikely.
+const SHADOW_CASCADE_ORDER_SHIFT: usize = SOURCE_ORDER_BITS;
+const SHADOW_CASCADE_ORDER_BITS: usize = 4;
+const SHADOW_CASCADE_ORDER_MAX: u8 = (1 << SHADOW_CASCADE_ORDER_BITS) - 1;
+const SHADOW_CASCADE_ORDER_MASK: u32 = (SHADOW_CASCADE_ORDER_MAX as u32) << SHADOW_CASCADE_ORDER_SHIFT;
+
+const CASCADE_LEVEL_SHIFT: usize = SOURCE_ORDER_BITS + SHADOW_CASCADE_ORDER_BITS;
+const CASCADE_LEVEL_BITS: usize = 4;
+const CASCADE_LEVEL_MAX: u8 = (1 << CASCADE_LEVEL_BITS) - 1;
+const CASCADE_LEVEL_MASK: u32 = (CASCADE_LEVEL_MAX as u32) << CASCADE_LEVEL_SHIFT;
+
+/// Stores the source order of a block, the cascade level it belongs to, and the
+/// counter needed to handle Shadow DOM cascade order properly.
 #[derive(Clone, Copy, Eq, MallocSizeOf, PartialEq)]
-struct SourceOrderAndCascadeLevel(u32);
+struct ApplicableDeclarationBits(u32);
 
-impl SourceOrderAndCascadeLevel {
-    fn new(source_order: u32, cascade_level: CascadeLevel) -> SourceOrderAndCascadeLevel {
+impl ApplicableDeclarationBits {
+    fn new(
+        source_order: u32,
+        cascade_level: CascadeLevel,
+        shadow_cascade_order: ShadowCascadeOrder,
+    ) -> Self {
+        debug_assert!(
+            cascade_level as u8 <= CASCADE_LEVEL_MAX,
+            "Gotta find more bits!"
+        );
         let mut bits = ::std::cmp::min(source_order, SOURCE_ORDER_MAX);
-        bits |= (cascade_level as u8 as u32) << SOURCE_ORDER_BITS;
-        SourceOrderAndCascadeLevel(bits)
+        bits |= ((shadow_cascade_order & SHADOW_CASCADE_ORDER_MAX) as u32) << SHADOW_CASCADE_ORDER_SHIFT;
+        bits |= (cascade_level as u8 as u32) << CASCADE_LEVEL_SHIFT;
+        ApplicableDeclarationBits(bits)
     }
 
-    fn order(&self) -> u32 {
-        self.0 & SOURCE_ORDER_MASK
+    fn source_order(&self) -> u32 {
+        (self.0 & SOURCE_ORDER_MASK) >> SOURCE_ORDER_SHIFT
+    }
+
+    fn shadow_cascade_order(&self) -> ShadowCascadeOrder {
+        ((self.0 & SHADOW_CASCADE_ORDER_MASK) >> SHADOW_CASCADE_ORDER_SHIFT) as ShadowCascadeOrder
     }
 
     fn level(&self) -> CascadeLevel {
-        unsafe {
-            // Transmute rather than shifting so that we're sure the compiler
-            // emits a simple byte-aligned load.
-            let as_bytes: [u8; 4] = mem::transmute(self.0);
-            CascadeLevel::from_byte(as_bytes[3])
-        }
+        let byte = ((self.0 & CASCADE_LEVEL_MASK) >> CASCADE_LEVEL_SHIFT) as u8;
+        unsafe { CascadeLevel::from_byte(byte) }
     }
 }
 
-impl Debug for SourceOrderAndCascadeLevel {
+impl Debug for ApplicableDeclarationBits {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("SourceOrderAndCascadeLevel")
-            .field("order", &self.order())
+        f.debug_struct("ApplicableDeclarationBits")
+            .field("source_order", &self.source_order())
+            .field("shadow_cascade_order", &self.shadow_cascade_order())
             .field("level", &self.level())
             .finish()
     }
@@ -79,8 +100,9 @@ pub struct ApplicableDeclarationBlock {
     /// The style source, either a style rule, or a property declaration block.
     #[ignore_malloc_size_of = "Arc"]
     pub source: StyleSource,
-    /// The source order of the block, and the cascade level it belongs to.
-    order_and_level: SourceOrderAndCascadeLevel,
+    /// The bits containing the source order, cascade level, and shadow cascade
+    /// order.
+    bits: ApplicableDeclarationBits,
     /// The specificity of the selector this block is represented by.
     pub specificity: u32,
 }
@@ -95,38 +117,45 @@ impl ApplicableDeclarationBlock {
     ) -> Self {
         ApplicableDeclarationBlock {
             source: StyleSource::Declarations(declarations),
-            order_and_level: SourceOrderAndCascadeLevel::new(0, level),
+            bits: ApplicableDeclarationBits::new(0, level, 0),
             specificity: 0,
         }
     }
 
     /// Constructs an applicable declaration block from the given components
     #[inline]
-    pub fn new(source: StyleSource, order: u32, level: CascadeLevel, specificity: u32) -> Self {
+    pub fn new(
+        source: StyleSource,
+        order: u32,
+        level: CascadeLevel,
+        specificity: u32,
+        shadow_cascade_order: ShadowCascadeOrder,
+    ) -> Self {
         ApplicableDeclarationBlock {
-            source: source,
-            order_and_level: SourceOrderAndCascadeLevel::new(order, level),
-            specificity: specificity,
+            source,
+            bits: ApplicableDeclarationBits::new(order, level, shadow_cascade_order),
+            specificity,
         }
     }
 
     /// Returns the source order of the block.
     #[inline]
     pub fn source_order(&self) -> u32 {
-        self.order_and_level.order()
+        self.bits.source_order()
     }
 
     /// Returns the cascade level of the block.
     #[inline]
     pub fn level(&self) -> CascadeLevel {
-        self.order_and_level.level()
+        self.bits.level()
     }
 
-    /// Convenience method to consume self and return the source alongside the
-    /// level.
+    /// Convenience method to consume self and return the right thing for the
+    /// rule tree to iterate over.
     #[inline]
-    pub fn order_and_level(self) -> (StyleSource, CascadeLevel) {
+    pub fn for_rule_tree(self) -> (StyleSource, CascadeLevel, ShadowCascadeOrder) {
         let level = self.level();
-        (self.source, level)
+        let cascade_order = self.bits.shadow_cascade_order();
+        (self.source, level, cascade_order)
     }
 }
diff --git a/components/style/build_gecko.rs b/components/style/build_gecko.rs
index 2d1db9e7037..95bb1622942 100644
--- a/components/style/build_gecko.rs
+++ b/components/style/build_gecko.rs
@@ -3,38 +3,19 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 mod common {
-    use std::{env, fs, io};
-    use std::path::{Path, PathBuf};
+    use std::env;
+    use std::path::PathBuf;
 
     lazy_static! {
         pub static ref OUTDIR_PATH: PathBuf =
             PathBuf::from(env::var_os("OUT_DIR").unwrap()).join("gecko");
     }
-
-    /// Copy contents of one directory into another.
-    /// It currently only does a shallow copy.
-    pub fn copy_dir<P, Q, F>(from: P, to: Q, callback: F) -> io::Result<()>
-    where
-        P: AsRef<Path>,
-        Q: AsRef<Path>,
-        F: Fn(&Path),
-    {
-        let to = to.as_ref();
-        for entry in from.as_ref().read_dir()? {
-            let entry = entry?;
-            let path = entry.path();
-            callback(&path);
-            fs::copy(&path, to.join(entry.file_name()))?;
-        }
-        Ok(())
-    }
 }
 
 #[cfg(feature = "bindgen")]
 mod bindings {
     use bindgen::{Builder, CodegenConfig};
-    use bindgen::callbacks::{EnumVariantCustomBehavior, EnumVariantValue, ParseCallbacks};
-    use regex::{Regex, RegexSet};
+    use regex::Regex;
     use std::cmp;
     use std::collections::{HashMap, HashSet};
     use std::env;
@@ -416,27 +397,6 @@ mod bindings {
     }
 
     fn generate_structs() {
-        #[derive(Debug)]
-        struct Callbacks(HashMap<String, RegexSet>);
-        impl ParseCallbacks for Callbacks {
-            fn enum_variant_behavior(
-                &self,
-                enum_name: Option<&str>,
-                variant_name: &str,
-                _variant_value: EnumVariantValue,
-            ) -> Option<EnumVariantCustomBehavior> {
-                enum_name
-                    .and_then(|enum_name| self.0.get(enum_name))
-                    .and_then(|regex| {
-                        if regex.is_match(variant_name) {
-                            Some(EnumVariantCustomBehavior::Constify)
-                        } else {
-                            None
-                        }
-                    })
-            }
-        }
-
         let builder = Builder::get_initial_builder()
             .enable_cxx_namespaces()
             .with_codegen_config(CodegenConfig {
@@ -452,21 +412,6 @@ mod bindings {
             .handle_str_items("whitelist-vars", |b, item| b.whitelist_var(item))
             .handle_str_items("whitelist-types", |b, item| b.whitelist_type(item))
             .handle_str_items("opaque-types", |b, item| b.opaque_type(item))
-            .handle_list("constified-enum-variants", |builder, iter| {
-                let mut map = HashMap::new();
-                for item in iter {
-                    let item = item.as_table().unwrap();
-                    let name = item["enum"].as_str().unwrap();
-                    let variants = item["variants"]
-                        .as_array()
-                        .unwrap()
-                        .as_slice()
-                        .iter()
-                        .map(|item| item.as_str().unwrap());
-                    map.insert(name.into(), RegexSet::new(variants).unwrap());
-                }
-                builder.parse_callbacks(Box::new(Callbacks(map)))
-            })
             .handle_table_items("mapped-generic-types", |builder, item| {
                 let generic = item["generic"].as_bool().unwrap();
                 let gecko = item["gecko"].as_str().unwrap();
@@ -650,23 +595,33 @@ mod bindings {
             generate_bindings(),
             generate_atoms(),
         }
-
-        // Copy all generated files to dist for the binding package
-        let path = DISTDIR_PATH.join("rust_bindings/style");
-        if path.exists() {
-            fs::remove_dir_all(&path).expect("Fail to remove binding dir in dist");
-        }
-        fs::create_dir_all(&path).expect("Fail to create bindings dir in dist");
-        copy_dir(&*OUTDIR_PATH, &path, |_| {}).expect("Fail to copy generated files to dist dir");
     }
 }
 
 #[cfg(not(feature = "bindgen"))]
 mod bindings {
-    use std::env;
-    use std::path::PathBuf;
+    use std::{env, fs, io};
+    use std::path::{Path, PathBuf};
     use super::common::*;
 
+    /// Copy contents of one directory into another.
+    /// It currently only does a shallow copy.
+    fn copy_dir<P, Q, F>(from: P, to: Q, callback: F) -> io::Result<()>
+    where
+        P: AsRef<Path>,
+        Q: AsRef<Path>,
+        F: Fn(&Path),
+    {
+        let to = to.as_ref();
+        for entry in from.as_ref().read_dir()? {
+            let entry = entry?;
+            let path = entry.path();
+            callback(&path);
+            fs::copy(&path, to.join(entry.file_name()))?;
+        }
+        Ok(())
+    }
+
     pub fn generate() {
         let dir = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap()).join("gecko/generated");
         println!("cargo:rerun-if-changed={}", dir.display());
diff --git a/components/style/font_face.rs b/components/style/font_face.rs
index a890822d02f..5a111925ae7 100644
--- a/components/style/font_face.rs
+++ b/components/style/font_face.rs
@@ -6,10 +6,6 @@
 //!
 //! [ff]: https://drafts.csswg.org/css-fonts/#at-font-face-rule
 
-#![deny(missing_docs)]
-
-#[cfg(feature = "gecko")]
-use computed_values::{font_stretch, font_style, font_weight};
 use cssparser::{AtRuleParser, DeclarationListParser, DeclarationParser, Parser};
 use cssparser::{CowRcStr, SourceLocation};
 #[cfg(feature = "gecko")]
@@ -26,8 +22,12 @@ use style_traits::{Comma, CssWriter, OneOrMoreSeparated, ParseError};
 use style_traits::{StyleParseErrorKind, ToCss};
 use style_traits::values::SequenceWriter;
 use values::computed::font::FamilyName;
+use values::generics::font::FontStyle as GenericFontStyle;
+use values::specified::Angle;
+use values::specified::font::{AbsoluteFontWeight, FontStretch as SpecifiedFontStretch};
 #[cfg(feature = "gecko")]
 use values::specified::font::{SpecifiedFontFeatureSettings, SpecifiedFontVariationSettings};
+use values::specified::font::SpecifiedFontStyle;
 use values::specified::url::SpecifiedUrl;
 
 /// A source for a font-face rule.
@@ -92,41 +92,97 @@ pub enum FontDisplay {
     Optional,
 }
 
-/// A font-weight value for a @font-face rule.
-/// The font-weight CSS property specifies the weight or boldness of the font.
-#[cfg(feature = "gecko")]
-#[derive(Clone, Debug, Eq, PartialEq, ToCss)]
-pub enum FontWeight {
-    /// Numeric font weights for fonts that provide more than just normal and bold.
-    Weight(font_weight::T),
-    /// Normal font weight. Same as 400.
-    Normal,
-    /// Bold font weight. Same as 700.
-    Bold,
-}
+/// The font-weight descriptor:
+///
+/// https://drafts.csswg.org/css-fonts-4/#descdef-font-face-font-weight
+#[derive(Clone, Debug, PartialEq, ToCss)]
+pub struct FontWeight(pub AbsoluteFontWeight, pub Option<AbsoluteFontWeight>);
 
-#[cfg(feature = "gecko")]
 impl Parse for FontWeight {
     fn parse<'i, 't>(
-        _: &ParserContext,
+        context: &ParserContext,
         input: &mut Parser<'i, 't>,
-    ) -> Result<FontWeight, ParseError<'i>> {
-        let result = input.try(|input| {
-            let ident = input.expect_ident().map_err(|_| ())?;
-            match_ignore_ascii_case! { &ident,
-                "normal" => Ok(FontWeight::Normal),
-                "bold" => Ok(FontWeight::Bold),
-                _ => Err(())
+    ) -> Result<Self, ParseError<'i>> {
+        let first = AbsoluteFontWeight::parse(context, input)?;
+        let second =
+            input.try(|input| AbsoluteFontWeight::parse(context, input)).ok();
+        Ok(FontWeight(first, second))
+    }
+}
+
+/// The font-stretch descriptor:
+///
+/// https://drafts.csswg.org/css-fonts-4/#descdef-font-face-font-stretch
+#[derive(Clone, Debug, PartialEq, ToCss)]
+pub struct FontStretch(pub SpecifiedFontStretch, pub Option<SpecifiedFontStretch>);
+
+impl Parse for FontStretch {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        let first = SpecifiedFontStretch::parse(context, input)?;
+        let second =
+            input.try(|input| SpecifiedFontStretch::parse(context, input)).ok();
+        Ok(FontStretch(first, second))
+    }
+}
+
+/// The font-style descriptor:
+///
+/// https://drafts.csswg.org/css-fonts-4/#descdef-font-face-font-style
+#[derive(Clone, Debug, PartialEq)]
+#[allow(missing_docs)]
+pub enum FontStyle {
+    Normal,
+    Italic,
+    Oblique(Angle, Angle),
+}
+
+impl Parse for FontStyle {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        let style = SpecifiedFontStyle::parse(context, input)?;
+        Ok(match style {
+            GenericFontStyle::Normal => FontStyle::Normal,
+            GenericFontStyle::Italic => FontStyle::Italic,
+            GenericFontStyle::Oblique(angle) => {
+                let second_angle = input.try(|input| {
+                    SpecifiedFontStyle::parse_angle(context, input)
+                }).unwrap_or_else(|_| angle.clone());
+
+                FontStyle::Oblique(angle, second_angle)
             }
-        });
-        result.or_else(|_| {
-            font_weight::T::from_int(input.expect_integer()?)
-                .map(FontWeight::Weight)
-                .map_err(|()| input.new_custom_error(StyleParseErrorKind::UnspecifiedError))
         })
     }
 }
 
+impl ToCss for FontStyle {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: fmt::Write,
+    {
+        match *self {
+            FontStyle::Normal => dest.write_str("normal"),
+            FontStyle::Italic => dest.write_str("italic"),
+            FontStyle::Oblique(ref first, ref second) => {
+                dest.write_str("oblique")?;
+                if *first != SpecifiedFontStyle::default_angle() || first != second {
+                    dest.write_char(' ')?;
+                    first.to_css(dest)?;
+                }
+                if first != second {
+                    dest.write_char(' ')?;
+                    second.to_css(dest)?;
+                }
+                Ok(())
+            }
+        }
+    }
+}
+
 /// Parse the block inside a `@font-face` rule.
 ///
 /// Note that the prelude parsing code lives in the `stylesheets` module.
@@ -403,16 +459,16 @@ font_face_descriptors! {
         "src" sources / mSrc: Vec<Source>,
     ]
     optional descriptors = [
-        /// The style of this font face
-        "font-style" style / mStyle: font_style::T,
+        /// The style of this font face.
+        "font-style" style / mStyle: FontStyle,
 
-        /// The weight of this font face
+        /// The weight of this font face.
         "font-weight" weight / mWeight: FontWeight,
 
-        /// The stretch of this font face
-        "font-stretch" stretch / mStretch: font_stretch::T,
+        /// The stretch of this font face.
+        "font-stretch" stretch / mStretch: FontStretch,
 
-        /// The display of this font face
+        /// The display of this font face.
         "font-display" display / mDisplay: FontDisplay,
 
         /// The ranges of code points outside of which this font face should not be used.
diff --git a/components/style/gecko/generated/bindings.rs b/components/style/gecko/generated/bindings.rs
index 508f9ce4345..d5c7443b5a3 100644
--- a/components/style/gecko/generated/bindings.rs
+++ b/components/style/gecko/generated/bindings.rs
@@ -232,6 +232,7 @@ use gecko_bindings::structs::nsresult;
 use gecko_bindings::structs::Loader;
 use gecko_bindings::structs::LoaderReusableStyleSheets;
 use gecko_bindings::structs::SheetLoadData;
+use gecko_bindings::structs::SheetLoadDataHolder;
 use gecko_bindings::structs::ServoStyleSheet;
 use gecko_bindings::structs::ServoComputedData;
 use gecko_bindings::structs::ComputedStyleStrong;
@@ -627,18 +628,36 @@ extern "C" {
         it: RawGeckoStyleChildrenIteratorBorrowedMut,
     ) -> RawGeckoNodeBorrowedOrNull;
 }
+extern "C" {
+    pub fn Gecko_AddRefSheetLoadDataHolderArbitraryThread(aPtr: *mut SheetLoadDataHolder);
+}
+extern "C" {
+    pub fn Gecko_ReleaseSheetLoadDataHolderArbitraryThread(aPtr: *mut SheetLoadDataHolder);
+}
+extern "C" {
+    pub fn Gecko_StyleSheet_FinishAsyncParse(
+        data: *mut SheetLoadDataHolder,
+        sheet_contents: RawServoStyleSheetContentsStrong,
+    );
+}
 extern "C" {
     pub fn Gecko_LoadStyleSheet(
         loader: *mut Loader,
         parent: *mut ServoStyleSheet,
         parent_load_data: *mut SheetLoadData,
         reusable_sheets: *mut LoaderReusableStyleSheets,
-        base_url_data: *mut RawGeckoURLExtraData,
-        url_bytes: *const u8,
-        url_length: u32,
+        url: ServoBundledURI,
         media_list: RawServoMediaListStrong,
     ) -> *mut ServoStyleSheet;
 }
+extern "C" {
+    pub fn Gecko_LoadStyleSheetAsync(
+        parent_data: *mut SheetLoadDataHolder,
+        url: ServoBundledURI,
+        media_list: RawServoMediaListStrong,
+        import_rule: RawServoImportRuleStrong,
+    );
+}
 extern "C" {
     pub fn Gecko_ElementState(element: RawGeckoElementBorrowed) -> u64;
 }
@@ -1996,8 +2015,7 @@ extern "C" {
         loader: *mut Loader,
         gecko_stylesheet: *mut ServoStyleSheet,
         load_data: *mut SheetLoadData,
-        data: *const u8,
-        data_len: usize,
+        bytes: *const nsACString,
         parsing_mode: SheetParsingMode,
         extra_data: *mut RawGeckoURLExtraData,
         line_number_offset: u32,
@@ -2005,6 +2023,16 @@ extern "C" {
         reusable_sheets: *mut LoaderReusableStyleSheets,
     ) -> RawServoStyleSheetContentsStrong;
 }
+extern "C" {
+    pub fn Servo_StyleSheet_FromUTF8BytesAsync(
+        load_data: *mut SheetLoadDataHolder,
+        extra_data: *mut RawGeckoURLExtraData,
+        bytes: *const nsACString,
+        parsing_mode: SheetParsingMode,
+        line_number_offset: u32,
+        quirks_mode: nsCompatibility,
+    );
+}
 extern "C" {
     pub fn Servo_StyleSheet_Empty(
         parsing_mode: SheetParsingMode,
@@ -2512,12 +2540,22 @@ extern "C" {
         pseudo_type: CSSPseudoElementType,
     ) -> bool;
 }
+extern "C" {
+    pub fn Servo_StyleRule_SetSelectorText(
+        sheet: RawServoStyleSheetContentsBorrowed,
+        rule: RawServoStyleRuleBorrowed,
+        text: *const nsAString,
+    ) -> bool;
+}
 extern "C" {
     pub fn Servo_ImportRule_GetHref(rule: RawServoImportRuleBorrowed, result: *mut nsAString);
 }
 extern "C" {
     pub fn Servo_ImportRule_GetSheet(rule: RawServoImportRuleBorrowed) -> *const ServoStyleSheet;
 }
+extern "C" {
+    pub fn Servo_ImportRule_SetSheet(rule: RawServoImportRuleBorrowed, sheet: *mut ServoStyleSheet);
+}
 extern "C" {
     pub fn Servo_Keyframe_GetKeyText(keyframe: RawServoKeyframeBorrowed, result: *mut nsAString);
 }
diff --git a/components/style/gecko/generated/structs.rs b/components/style/gecko/generated/structs.rs
index ebe6b79afbc..f88b116b646 100644
--- a/components/style/gecko/generated/structs.rs
+++ b/components/style/gecko/generated/structs.rs
@@ -149,15 +149,15 @@ pub mod root {
     pub const NS_FONT_WEIGHT_NORMAL: u32 = 400;
     pub const NS_FONT_WEIGHT_BOLD: u32 = 700;
     pub const NS_FONT_WEIGHT_THIN: u32 = 100;
-    pub const NS_FONT_STRETCH_ULTRA_CONDENSED: i32 = -4;
-    pub const NS_FONT_STRETCH_EXTRA_CONDENSED: i32 = -3;
-    pub const NS_FONT_STRETCH_CONDENSED: i32 = -2;
-    pub const NS_FONT_STRETCH_SEMI_CONDENSED: i32 = -1;
-    pub const NS_FONT_STRETCH_NORMAL: u32 = 0;
-    pub const NS_FONT_STRETCH_SEMI_EXPANDED: u32 = 1;
-    pub const NS_FONT_STRETCH_EXPANDED: u32 = 2;
-    pub const NS_FONT_STRETCH_EXTRA_EXPANDED: u32 = 3;
-    pub const NS_FONT_STRETCH_ULTRA_EXPANDED: u32 = 4;
+    pub const NS_FONT_STRETCH_ULTRA_CONDENSED: u32 = 50;
+    pub const NS_FONT_STRETCH_EXTRA_CONDENSED: u32 = 62;
+    pub const NS_FONT_STRETCH_CONDENSED: u32 = 75;
+    pub const NS_FONT_STRETCH_SEMI_CONDENSED: u32 = 87;
+    pub const NS_FONT_STRETCH_NORMAL: u32 = 100;
+    pub const NS_FONT_STRETCH_SEMI_EXPANDED: u32 = 112;
+    pub const NS_FONT_STRETCH_EXPANDED: u32 = 125;
+    pub const NS_FONT_STRETCH_EXTRA_EXPANDED: u32 = 150;
+    pub const NS_FONT_STRETCH_ULTRA_EXPANDED: u32 = 200;
     pub const NS_FONT_SMOOTHING_AUTO: u32 = 0;
     pub const NS_FONT_SMOOTHING_GRAYSCALE: u32 = 1;
     pub const NS_FONT_KERNING_AUTO: u32 = 0;
@@ -429,15 +429,15 @@ pub mod root {
     pub const NS_STYLE_FONT_SIZE_LARGER: u32 = 8;
     pub const NS_STYLE_FONT_SIZE_SMALLER: u32 = 9;
     pub const NS_STYLE_FONT_SIZE_NO_KEYWORD: u32 = 10;
-    pub const NS_STYLE_FONT_STRETCH_ULTRA_CONDENSED: i32 = -4;
-    pub const NS_STYLE_FONT_STRETCH_EXTRA_CONDENSED: i32 = -3;
-    pub const NS_STYLE_FONT_STRETCH_CONDENSED: i32 = -2;
-    pub const NS_STYLE_FONT_STRETCH_SEMI_CONDENSED: i32 = -1;
-    pub const NS_STYLE_FONT_STRETCH_NORMAL: u32 = 0;
-    pub const NS_STYLE_FONT_STRETCH_SEMI_EXPANDED: u32 = 1;
-    pub const NS_STYLE_FONT_STRETCH_EXPANDED: u32 = 2;
-    pub const NS_STYLE_FONT_STRETCH_EXTRA_EXPANDED: u32 = 3;
-    pub const NS_STYLE_FONT_STRETCH_ULTRA_EXPANDED: u32 = 4;
+    pub const NS_STYLE_FONT_STRETCH_ULTRA_CONDENSED: u32 = 50;
+    pub const NS_STYLE_FONT_STRETCH_EXTRA_CONDENSED: u32 = 62;
+    pub const NS_STYLE_FONT_STRETCH_CONDENSED: u32 = 75;
+    pub const NS_STYLE_FONT_STRETCH_SEMI_CONDENSED: u32 = 87;
+    pub const NS_STYLE_FONT_STRETCH_NORMAL: u32 = 100;
+    pub const NS_STYLE_FONT_STRETCH_SEMI_EXPANDED: u32 = 112;
+    pub const NS_STYLE_FONT_STRETCH_EXPANDED: u32 = 125;
+    pub const NS_STYLE_FONT_STRETCH_EXTRA_EXPANDED: u32 = 150;
+    pub const NS_STYLE_FONT_STRETCH_ULTRA_EXPANDED: u32 = 200;
     pub const NS_STYLE_FONT_CAPTION: u32 = 1;
     pub const NS_STYLE_FONT_ICON: u32 = 2;
     pub const NS_STYLE_FONT_MENU: u32 = 3;
@@ -6471,6 +6471,8 @@ pub mod root {
                     __bindgen_bitfield_unit
                 }
             }
+            pub type SheetLoadDataHolder =
+                root::nsMainThreadPtrHolder<root::mozilla::css::SheetLoadData>;
             #[repr(C)]
             #[derive(Debug, Copy)]
             pub struct ImageLoader {
@@ -17422,6 +17424,16 @@ pub mod root {
         );
     }
     #[repr(C)]
+    #[derive(Debug)]
+    pub struct nsMainThreadPtrHolder<T> {
+        pub mRefCnt: root::mozilla::ThreadSafeAutoRefCnt,
+        pub mRawPtr: *mut T,
+        pub mStrict: bool,
+        pub mMainThreadEventTarget: root::nsCOMPtr,
+        pub mName: *const ::std::os::raw::c_char,
+        pub _phantom_0: ::std::marker::PhantomData<::std::cell::UnsafeCell<T>>,
+    }
+    #[repr(C)]
     #[derive(Debug, Copy)]
     pub struct nsISerializable {
         pub _base: root::nsISupports,
@@ -18354,18 +18366,6 @@ pub mod root {
     pub type nsRefPtrHashKey_KeyTypePointer<T> = *mut T;
     pub const nsRefPtrHashKey_ALLOW_MEMMOVE: root::nsRefPtrHashKey__bindgen_ty_1 = 0;
     pub type nsRefPtrHashKey__bindgen_ty_1 = i32;
-    pub const nsCSSPropertyID_eCSSProperty_COUNT_no_shorthands: root::nsCSSPropertyID =
-        nsCSSPropertyID::eCSSProperty_all;
-    pub const nsCSSPropertyID_eCSSProperty_COUNT_DUMMY: root::nsCSSPropertyID =
-        nsCSSPropertyID::eCSSProperty_z_index;
-    pub const nsCSSPropertyID_eCSSProperty_COUNT: root::nsCSSPropertyID =
-        nsCSSPropertyID::eCSSPropertyAlias_WordWrap;
-    pub const nsCSSPropertyID_eCSSProperty_COUNT_DUMMY2: root::nsCSSPropertyID =
-        nsCSSPropertyID::eCSSProperty_transition;
-    pub const nsCSSPropertyID_eCSSProperty_COUNT_with_aliases: root::nsCSSPropertyID =
-        nsCSSPropertyID::eCSSPropertyExtra_no_properties;
-    pub const nsCSSPropertyID_eCSSProperty_COUNT_DUMMY3: root::nsCSSPropertyID =
-        nsCSSPropertyID::eCSSPropertyAlias_WebkitMaskSize;
     #[repr(i32)]
     #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
     pub enum nsCSSPropertyID {
@@ -18516,11 +18516,11 @@ pub mod root {
         eCSSProperty_grid_template_rows = 143,
         eCSSProperty_height = 144,
         eCSSProperty_hyphens = 145,
-        eCSSProperty_initial_letter = 146,
-        eCSSProperty_image_orientation = 147,
-        eCSSProperty__moz_image_region = 148,
-        eCSSProperty_image_rendering = 149,
-        eCSSProperty_ime_mode = 150,
+        eCSSProperty_image_orientation = 146,
+        eCSSProperty__moz_image_region = 147,
+        eCSSProperty_image_rendering = 148,
+        eCSSProperty_ime_mode = 149,
+        eCSSProperty_initial_letter = 150,
         eCSSProperty_inline_size = 151,
         eCSSProperty_isolation = 152,
         eCSSProperty_justify_content = 153,
@@ -18587,113 +18587,113 @@ pub mod root {
         eCSSProperty_outline_width = 214,
         eCSSProperty_overflow_clip_box_block = 215,
         eCSSProperty_overflow_clip_box_inline = 216,
-        eCSSProperty_overflow_x = 217,
-        eCSSProperty_overflow_y = 218,
-        eCSSProperty_padding_block_end = 219,
-        eCSSProperty_padding_block_start = 220,
-        eCSSProperty_padding_bottom = 221,
-        eCSSProperty_padding_inline_end = 222,
-        eCSSProperty_padding_inline_start = 223,
-        eCSSProperty_padding_left = 224,
-        eCSSProperty_padding_right = 225,
-        eCSSProperty_padding_top = 226,
-        eCSSProperty_page_break_after = 227,
-        eCSSProperty_page_break_before = 228,
-        eCSSProperty_page_break_inside = 229,
-        eCSSProperty_paint_order = 230,
-        eCSSProperty_perspective = 231,
-        eCSSProperty_perspective_origin = 232,
-        eCSSProperty_pointer_events = 233,
-        eCSSProperty_position = 234,
-        eCSSProperty_quotes = 235,
-        eCSSProperty_resize = 236,
-        eCSSProperty_right = 237,
-        eCSSProperty_rotate = 238,
-        eCSSProperty_ruby_align = 239,
-        eCSSProperty_ruby_position = 240,
-        eCSSProperty__moz_script_level = 241,
-        eCSSProperty__moz_script_min_size = 242,
-        eCSSProperty__moz_script_size_multiplier = 243,
-        eCSSProperty_scroll_behavior = 244,
-        eCSSProperty_overscroll_behavior_x = 245,
-        eCSSProperty_overscroll_behavior_y = 246,
-        eCSSProperty_scroll_snap_coordinate = 247,
-        eCSSProperty_scroll_snap_destination = 248,
-        eCSSProperty_scroll_snap_points_x = 249,
-        eCSSProperty_scroll_snap_points_y = 250,
-        eCSSProperty_scroll_snap_type_x = 251,
-        eCSSProperty_scroll_snap_type_y = 252,
-        eCSSProperty_shape_image_threshold = 253,
-        eCSSProperty_shape_outside = 254,
-        eCSSProperty_shape_rendering = 255,
-        eCSSProperty__x_span = 256,
-        eCSSProperty__moz_stack_sizing = 257,
-        eCSSProperty_stop_color = 258,
-        eCSSProperty_stop_opacity = 259,
-        eCSSProperty_stroke = 260,
-        eCSSProperty_stroke_dasharray = 261,
-        eCSSProperty_stroke_dashoffset = 262,
-        eCSSProperty_stroke_linecap = 263,
-        eCSSProperty_stroke_linejoin = 264,
-        eCSSProperty_stroke_miterlimit = 265,
-        eCSSProperty_stroke_opacity = 266,
-        eCSSProperty_stroke_width = 267,
-        eCSSProperty__moz_tab_size = 268,
-        eCSSProperty_table_layout = 269,
-        eCSSProperty_text_align = 270,
-        eCSSProperty_text_align_last = 271,
-        eCSSProperty_text_anchor = 272,
-        eCSSProperty_text_combine_upright = 273,
-        eCSSProperty_text_decoration_color = 274,
-        eCSSProperty_text_decoration_line = 275,
-        eCSSProperty_text_decoration_style = 276,
-        eCSSProperty_text_emphasis_color = 277,
-        eCSSProperty_text_emphasis_position = 278,
-        eCSSProperty_text_emphasis_style = 279,
-        eCSSProperty__webkit_text_fill_color = 280,
-        eCSSProperty_text_indent = 281,
-        eCSSProperty_text_justify = 282,
-        eCSSProperty_text_orientation = 283,
-        eCSSProperty_text_overflow = 284,
-        eCSSProperty_text_rendering = 285,
-        eCSSProperty_text_shadow = 286,
-        eCSSProperty__moz_text_size_adjust = 287,
-        eCSSProperty__webkit_text_stroke_color = 288,
-        eCSSProperty__webkit_text_stroke_width = 289,
-        eCSSProperty_scale = 290,
-        eCSSProperty_text_transform = 291,
-        eCSSProperty__x_text_zoom = 292,
-        eCSSProperty_top = 293,
-        eCSSProperty__moz_top_layer = 294,
-        eCSSProperty_touch_action = 295,
-        eCSSProperty_transform = 296,
-        eCSSProperty_transform_box = 297,
-        eCSSProperty_transform_origin = 298,
-        eCSSProperty_transform_style = 299,
-        eCSSProperty_transition_delay = 300,
-        eCSSProperty_transition_duration = 301,
-        eCSSProperty_transition_property = 302,
-        eCSSProperty_transition_timing_function = 303,
-        eCSSProperty_translate = 304,
-        eCSSProperty_unicode_bidi = 305,
-        eCSSProperty__moz_user_focus = 306,
-        eCSSProperty__moz_user_input = 307,
-        eCSSProperty__moz_user_modify = 308,
-        eCSSProperty__moz_user_select = 309,
-        eCSSProperty_vector_effect = 310,
-        eCSSProperty_vertical_align = 311,
-        eCSSProperty_visibility = 312,
-        eCSSProperty_white_space = 313,
-        eCSSProperty_width = 314,
-        eCSSProperty_will_change = 315,
-        eCSSProperty__moz_window_dragging = 316,
-        eCSSProperty__moz_window_shadow = 317,
+        eCSSProperty_overflow_wrap = 217,
+        eCSSProperty_overflow_x = 218,
+        eCSSProperty_overflow_y = 219,
+        eCSSProperty_overscroll_behavior_x = 220,
+        eCSSProperty_overscroll_behavior_y = 221,
+        eCSSProperty_padding_block_end = 222,
+        eCSSProperty_padding_block_start = 223,
+        eCSSProperty_padding_bottom = 224,
+        eCSSProperty_padding_inline_end = 225,
+        eCSSProperty_padding_inline_start = 226,
+        eCSSProperty_padding_left = 227,
+        eCSSProperty_padding_right = 228,
+        eCSSProperty_padding_top = 229,
+        eCSSProperty_page_break_after = 230,
+        eCSSProperty_page_break_before = 231,
+        eCSSProperty_page_break_inside = 232,
+        eCSSProperty_paint_order = 233,
+        eCSSProperty_perspective = 234,
+        eCSSProperty_perspective_origin = 235,
+        eCSSProperty_pointer_events = 236,
+        eCSSProperty_position = 237,
+        eCSSProperty_quotes = 238,
+        eCSSProperty_resize = 239,
+        eCSSProperty_right = 240,
+        eCSSProperty_rotate = 241,
+        eCSSProperty_ruby_align = 242,
+        eCSSProperty_ruby_position = 243,
+        eCSSProperty_scale = 244,
+        eCSSProperty__moz_script_level = 245,
+        eCSSProperty__moz_script_min_size = 246,
+        eCSSProperty__moz_script_size_multiplier = 247,
+        eCSSProperty_scroll_behavior = 248,
+        eCSSProperty_scroll_snap_coordinate = 249,
+        eCSSProperty_scroll_snap_destination = 250,
+        eCSSProperty_scroll_snap_points_x = 251,
+        eCSSProperty_scroll_snap_points_y = 252,
+        eCSSProperty_scroll_snap_type_x = 253,
+        eCSSProperty_scroll_snap_type_y = 254,
+        eCSSProperty_shape_image_threshold = 255,
+        eCSSProperty_shape_outside = 256,
+        eCSSProperty_shape_rendering = 257,
+        eCSSProperty__x_span = 258,
+        eCSSProperty__moz_stack_sizing = 259,
+        eCSSProperty_stop_color = 260,
+        eCSSProperty_stop_opacity = 261,
+        eCSSProperty_stroke = 262,
+        eCSSProperty_stroke_dasharray = 263,
+        eCSSProperty_stroke_dashoffset = 264,
+        eCSSProperty_stroke_linecap = 265,
+        eCSSProperty_stroke_linejoin = 266,
+        eCSSProperty_stroke_miterlimit = 267,
+        eCSSProperty_stroke_opacity = 268,
+        eCSSProperty_stroke_width = 269,
+        eCSSProperty__moz_tab_size = 270,
+        eCSSProperty_table_layout = 271,
+        eCSSProperty_text_align = 272,
+        eCSSProperty_text_align_last = 273,
+        eCSSProperty_text_anchor = 274,
+        eCSSProperty_text_combine_upright = 275,
+        eCSSProperty_text_decoration_color = 276,
+        eCSSProperty_text_decoration_line = 277,
+        eCSSProperty_text_decoration_style = 278,
+        eCSSProperty_text_emphasis_color = 279,
+        eCSSProperty_text_emphasis_position = 280,
+        eCSSProperty_text_emphasis_style = 281,
+        eCSSProperty__webkit_text_fill_color = 282,
+        eCSSProperty_text_indent = 283,
+        eCSSProperty_text_justify = 284,
+        eCSSProperty_text_orientation = 285,
+        eCSSProperty_text_overflow = 286,
+        eCSSProperty_text_rendering = 287,
+        eCSSProperty_text_shadow = 288,
+        eCSSProperty__moz_text_size_adjust = 289,
+        eCSSProperty__webkit_text_stroke_color = 290,
+        eCSSProperty__webkit_text_stroke_width = 291,
+        eCSSProperty_text_transform = 292,
+        eCSSProperty__x_text_zoom = 293,
+        eCSSProperty_top = 294,
+        eCSSProperty__moz_top_layer = 295,
+        eCSSProperty_touch_action = 296,
+        eCSSProperty_transform = 297,
+        eCSSProperty_transform_box = 298,
+        eCSSProperty_transform_origin = 299,
+        eCSSProperty_transform_style = 300,
+        eCSSProperty_transition_delay = 301,
+        eCSSProperty_transition_duration = 302,
+        eCSSProperty_transition_property = 303,
+        eCSSProperty_transition_timing_function = 304,
+        eCSSProperty_translate = 305,
+        eCSSProperty_unicode_bidi = 306,
+        eCSSProperty__moz_user_focus = 307,
+        eCSSProperty__moz_user_input = 308,
+        eCSSProperty__moz_user_modify = 309,
+        eCSSProperty__moz_user_select = 310,
+        eCSSProperty_vector_effect = 311,
+        eCSSProperty_vertical_align = 312,
+        eCSSProperty_visibility = 313,
+        eCSSProperty_white_space = 314,
+        eCSSProperty_width = 315,
+        eCSSProperty_will_change = 316,
+        eCSSProperty__moz_window_dragging = 317,
         eCSSProperty__moz_window_opacity = 318,
-        eCSSProperty__moz_window_transform = 319,
-        eCSSProperty__moz_window_transform_origin = 320,
-        eCSSProperty_word_break = 321,
-        eCSSProperty_word_spacing = 322,
-        eCSSProperty_overflow_wrap = 323,
+        eCSSProperty__moz_window_shadow = 319,
+        eCSSProperty__moz_window_transform = 320,
+        eCSSProperty__moz_window_transform_origin = 321,
+        eCSSProperty_word_break = 322,
+        eCSSProperty_word_spacing = 323,
         eCSSProperty_writing_mode = 324,
         eCSSProperty_z_index = 325,
         eCSSProperty_all = 326,
@@ -18735,132 +18735,129 @@ pub mod root {
         eCSSProperty__moz_outline_radius = 362,
         eCSSProperty_overflow = 363,
         eCSSProperty_overflow_clip_box = 364,
-        eCSSProperty_padding = 365,
-        eCSSProperty_place_content = 366,
-        eCSSProperty_place_items = 367,
-        eCSSProperty_place_self = 368,
-        eCSSProperty_overscroll_behavior = 369,
+        eCSSProperty_overscroll_behavior = 365,
+        eCSSProperty_padding = 366,
+        eCSSProperty_place_content = 367,
+        eCSSProperty_place_items = 368,
+        eCSSProperty_place_self = 369,
         eCSSProperty_scroll_snap_type = 370,
         eCSSProperty_text_decoration = 371,
         eCSSProperty_text_emphasis = 372,
         eCSSProperty__webkit_text_stroke = 373,
         eCSSProperty_transition = 374,
-        eCSSPropertyAlias_WordWrap = 375,
-        eCSSPropertyAlias_MozTransform = 376,
-        eCSSPropertyAlias_MozTransformOrigin = 377,
-        eCSSPropertyAlias_MozPerspectiveOrigin = 378,
-        eCSSPropertyAlias_MozPerspective = 379,
-        eCSSPropertyAlias_MozTransformStyle = 380,
-        eCSSPropertyAlias_MozBackfaceVisibility = 381,
-        eCSSPropertyAlias_MozBorderImage = 382,
-        eCSSPropertyAlias_MozTransition = 383,
-        eCSSPropertyAlias_MozTransitionDelay = 384,
-        eCSSPropertyAlias_MozTransitionDuration = 385,
-        eCSSPropertyAlias_MozTransitionProperty = 386,
-        eCSSPropertyAlias_MozTransitionTimingFunction = 387,
-        eCSSPropertyAlias_MozAnimation = 388,
-        eCSSPropertyAlias_MozAnimationDelay = 389,
-        eCSSPropertyAlias_MozAnimationDirection = 390,
-        eCSSPropertyAlias_MozAnimationDuration = 391,
-        eCSSPropertyAlias_MozAnimationFillMode = 392,
-        eCSSPropertyAlias_MozAnimationIterationCount = 393,
-        eCSSPropertyAlias_MozAnimationName = 394,
-        eCSSPropertyAlias_MozAnimationPlayState = 395,
-        eCSSPropertyAlias_MozAnimationTimingFunction = 396,
-        eCSSPropertyAlias_MozBoxSizing = 397,
-        eCSSPropertyAlias_MozFontFeatureSettings = 398,
-        eCSSPropertyAlias_MozFontLanguageOverride = 399,
-        eCSSPropertyAlias_MozPaddingEnd = 400,
-        eCSSPropertyAlias_MozPaddingStart = 401,
-        eCSSPropertyAlias_MozMarginEnd = 402,
-        eCSSPropertyAlias_MozMarginStart = 403,
-        eCSSPropertyAlias_MozBorderEnd = 404,
-        eCSSPropertyAlias_MozBorderEndColor = 405,
-        eCSSPropertyAlias_MozBorderEndStyle = 406,
-        eCSSPropertyAlias_MozBorderEndWidth = 407,
-        eCSSPropertyAlias_MozBorderStart = 408,
-        eCSSPropertyAlias_MozBorderStartColor = 409,
-        eCSSPropertyAlias_MozBorderStartStyle = 410,
-        eCSSPropertyAlias_MozBorderStartWidth = 411,
-        eCSSPropertyAlias_MozHyphens = 412,
-        eCSSPropertyAlias_MozColumnCount = 413,
-        eCSSPropertyAlias_MozColumnFill = 414,
-        eCSSPropertyAlias_MozColumnGap = 415,
-        eCSSPropertyAlias_MozColumnRule = 416,
-        eCSSPropertyAlias_MozColumnRuleColor = 417,
-        eCSSPropertyAlias_MozColumnRuleStyle = 418,
-        eCSSPropertyAlias_MozColumnRuleWidth = 419,
-        eCSSPropertyAlias_MozColumnSpan = 420,
-        eCSSPropertyAlias_MozColumnWidth = 421,
-        eCSSPropertyAlias_MozColumns = 422,
-        eCSSPropertyAlias_WebkitAnimation = 423,
-        eCSSPropertyAlias_WebkitAnimationDelay = 424,
-        eCSSPropertyAlias_WebkitAnimationDirection = 425,
-        eCSSPropertyAlias_WebkitAnimationDuration = 426,
-        eCSSPropertyAlias_WebkitAnimationFillMode = 427,
-        eCSSPropertyAlias_WebkitAnimationIterationCount = 428,
-        eCSSPropertyAlias_WebkitAnimationName = 429,
-        eCSSPropertyAlias_WebkitAnimationPlayState = 430,
-        eCSSPropertyAlias_WebkitAnimationTimingFunction = 431,
-        eCSSPropertyAlias_WebkitFilter = 432,
-        eCSSPropertyAlias_WebkitTextSizeAdjust = 433,
-        eCSSPropertyAlias_WebkitTransform = 434,
-        eCSSPropertyAlias_WebkitTransformOrigin = 435,
-        eCSSPropertyAlias_WebkitTransformStyle = 436,
-        eCSSPropertyAlias_WebkitBackfaceVisibility = 437,
-        eCSSPropertyAlias_WebkitPerspective = 438,
-        eCSSPropertyAlias_WebkitPerspectiveOrigin = 439,
-        eCSSPropertyAlias_WebkitTransition = 440,
-        eCSSPropertyAlias_WebkitTransitionDelay = 441,
-        eCSSPropertyAlias_WebkitTransitionDuration = 442,
-        eCSSPropertyAlias_WebkitTransitionProperty = 443,
-        eCSSPropertyAlias_WebkitTransitionTimingFunction = 444,
-        eCSSPropertyAlias_WebkitBorderRadius = 445,
-        eCSSPropertyAlias_WebkitBorderTopLeftRadius = 446,
-        eCSSPropertyAlias_WebkitBorderTopRightRadius = 447,
-        eCSSPropertyAlias_WebkitBorderBottomLeftRadius = 448,
-        eCSSPropertyAlias_WebkitBorderBottomRightRadius = 449,
-        eCSSPropertyAlias_WebkitBackgroundClip = 450,
-        eCSSPropertyAlias_WebkitBackgroundOrigin = 451,
-        eCSSPropertyAlias_WebkitBackgroundSize = 452,
-        eCSSPropertyAlias_WebkitBorderImage = 453,
-        eCSSPropertyAlias_WebkitBoxShadow = 454,
-        eCSSPropertyAlias_WebkitBoxSizing = 455,
-        eCSSPropertyAlias_WebkitBoxFlex = 456,
-        eCSSPropertyAlias_WebkitBoxOrdinalGroup = 457,
-        eCSSPropertyAlias_WebkitBoxOrient = 458,
-        eCSSPropertyAlias_WebkitBoxDirection = 459,
-        eCSSPropertyAlias_WebkitBoxAlign = 460,
-        eCSSPropertyAlias_WebkitBoxPack = 461,
-        eCSSPropertyAlias_WebkitFlexDirection = 462,
-        eCSSPropertyAlias_WebkitFlexWrap = 463,
-        eCSSPropertyAlias_WebkitFlexFlow = 464,
-        eCSSPropertyAlias_WebkitOrder = 465,
-        eCSSPropertyAlias_WebkitFlex = 466,
-        eCSSPropertyAlias_WebkitFlexGrow = 467,
-        eCSSPropertyAlias_WebkitFlexShrink = 468,
-        eCSSPropertyAlias_WebkitFlexBasis = 469,
-        eCSSPropertyAlias_WebkitJustifyContent = 470,
-        eCSSPropertyAlias_WebkitAlignItems = 471,
-        eCSSPropertyAlias_WebkitAlignSelf = 472,
-        eCSSPropertyAlias_WebkitAlignContent = 473,
-        eCSSPropertyAlias_WebkitUserSelect = 474,
-        eCSSPropertyAlias_WebkitMask = 475,
-        eCSSPropertyAlias_WebkitMaskClip = 476,
-        eCSSPropertyAlias_WebkitMaskComposite = 477,
-        eCSSPropertyAlias_WebkitMaskImage = 478,
-        eCSSPropertyAlias_WebkitMaskOrigin = 479,
-        eCSSPropertyAlias_WebkitMaskPosition = 480,
-        eCSSPropertyAlias_WebkitMaskPositionX = 481,
-        eCSSPropertyAlias_WebkitMaskPositionY = 482,
-        eCSSPropertyAlias_WebkitMaskRepeat = 483,
-        eCSSPropertyAlias_WebkitMaskSize = 484,
+        eCSSPropertyAlias__moz_animation = 375,
+        eCSSPropertyAlias__moz_animation_delay = 376,
+        eCSSPropertyAlias__moz_animation_direction = 377,
+        eCSSPropertyAlias__moz_animation_duration = 378,
+        eCSSPropertyAlias__moz_animation_fill_mode = 379,
+        eCSSPropertyAlias__moz_animation_iteration_count = 380,
+        eCSSPropertyAlias__moz_animation_name = 381,
+        eCSSPropertyAlias__moz_animation_play_state = 382,
+        eCSSPropertyAlias__moz_animation_timing_function = 383,
+        eCSSPropertyAlias__moz_backface_visibility = 384,
+        eCSSPropertyAlias__moz_border_end = 385,
+        eCSSPropertyAlias__moz_border_end_color = 386,
+        eCSSPropertyAlias__moz_border_end_style = 387,
+        eCSSPropertyAlias__moz_border_end_width = 388,
+        eCSSPropertyAlias__moz_border_image = 389,
+        eCSSPropertyAlias__moz_border_start = 390,
+        eCSSPropertyAlias__moz_border_start_color = 391,
+        eCSSPropertyAlias__moz_border_start_style = 392,
+        eCSSPropertyAlias__moz_border_start_width = 393,
+        eCSSPropertyAlias__moz_box_sizing = 394,
+        eCSSPropertyAlias__moz_column_count = 395,
+        eCSSPropertyAlias__moz_column_fill = 396,
+        eCSSPropertyAlias__moz_column_gap = 397,
+        eCSSPropertyAlias__moz_column_rule = 398,
+        eCSSPropertyAlias__moz_column_rule_color = 399,
+        eCSSPropertyAlias__moz_column_rule_style = 400,
+        eCSSPropertyAlias__moz_column_rule_width = 401,
+        eCSSPropertyAlias__moz_column_span = 402,
+        eCSSPropertyAlias__moz_column_width = 403,
+        eCSSPropertyAlias__moz_columns = 404,
+        eCSSPropertyAlias__moz_font_feature_settings = 405,
+        eCSSPropertyAlias__moz_font_language_override = 406,
+        eCSSPropertyAlias__moz_hyphens = 407,
+        eCSSPropertyAlias__moz_margin_end = 408,
+        eCSSPropertyAlias__moz_margin_start = 409,
+        eCSSPropertyAlias__moz_padding_end = 410,
+        eCSSPropertyAlias__moz_padding_start = 411,
+        eCSSPropertyAlias__moz_perspective = 412,
+        eCSSPropertyAlias__moz_perspective_origin = 413,
+        eCSSPropertyAlias__moz_transform = 414,
+        eCSSPropertyAlias__moz_transform_origin = 415,
+        eCSSPropertyAlias__moz_transform_style = 416,
+        eCSSPropertyAlias__moz_transition = 417,
+        eCSSPropertyAlias__moz_transition_delay = 418,
+        eCSSPropertyAlias__moz_transition_duration = 419,
+        eCSSPropertyAlias__moz_transition_property = 420,
+        eCSSPropertyAlias__moz_transition_timing_function = 421,
+        eCSSPropertyAlias__webkit_align_content = 422,
+        eCSSPropertyAlias__webkit_align_items = 423,
+        eCSSPropertyAlias__webkit_align_self = 424,
+        eCSSPropertyAlias__webkit_animation = 425,
+        eCSSPropertyAlias__webkit_animation_delay = 426,
+        eCSSPropertyAlias__webkit_animation_direction = 427,
+        eCSSPropertyAlias__webkit_animation_duration = 428,
+        eCSSPropertyAlias__webkit_animation_fill_mode = 429,
+        eCSSPropertyAlias__webkit_animation_iteration_count = 430,
+        eCSSPropertyAlias__webkit_animation_name = 431,
+        eCSSPropertyAlias__webkit_animation_play_state = 432,
+        eCSSPropertyAlias__webkit_animation_timing_function = 433,
+        eCSSPropertyAlias__webkit_backface_visibility = 434,
+        eCSSPropertyAlias__webkit_background_clip = 435,
+        eCSSPropertyAlias__webkit_background_origin = 436,
+        eCSSPropertyAlias__webkit_background_size = 437,
+        eCSSPropertyAlias__webkit_border_bottom_left_radius = 438,
+        eCSSPropertyAlias__webkit_border_bottom_right_radius = 439,
+        eCSSPropertyAlias__webkit_border_image = 440,
+        eCSSPropertyAlias__webkit_border_radius = 441,
+        eCSSPropertyAlias__webkit_border_top_left_radius = 442,
+        eCSSPropertyAlias__webkit_border_top_right_radius = 443,
+        eCSSPropertyAlias__webkit_box_align = 444,
+        eCSSPropertyAlias__webkit_box_direction = 445,
+        eCSSPropertyAlias__webkit_box_flex = 446,
+        eCSSPropertyAlias__webkit_box_ordinal_group = 447,
+        eCSSPropertyAlias__webkit_box_orient = 448,
+        eCSSPropertyAlias__webkit_box_pack = 449,
+        eCSSPropertyAlias__webkit_box_shadow = 450,
+        eCSSPropertyAlias__webkit_box_sizing = 451,
+        eCSSPropertyAlias__webkit_filter = 452,
+        eCSSPropertyAlias__webkit_flex = 453,
+        eCSSPropertyAlias__webkit_flex_basis = 454,
+        eCSSPropertyAlias__webkit_flex_direction = 455,
+        eCSSPropertyAlias__webkit_flex_flow = 456,
+        eCSSPropertyAlias__webkit_flex_grow = 457,
+        eCSSPropertyAlias__webkit_flex_shrink = 458,
+        eCSSPropertyAlias__webkit_flex_wrap = 459,
+        eCSSPropertyAlias__webkit_justify_content = 460,
+        eCSSPropertyAlias__webkit_mask = 461,
+        eCSSPropertyAlias__webkit_mask_clip = 462,
+        eCSSPropertyAlias__webkit_mask_composite = 463,
+        eCSSPropertyAlias__webkit_mask_image = 464,
+        eCSSPropertyAlias__webkit_mask_origin = 465,
+        eCSSPropertyAlias__webkit_mask_position = 466,
+        eCSSPropertyAlias__webkit_mask_position_x = 467,
+        eCSSPropertyAlias__webkit_mask_position_y = 468,
+        eCSSPropertyAlias__webkit_mask_repeat = 469,
+        eCSSPropertyAlias__webkit_mask_size = 470,
+        eCSSPropertyAlias__webkit_order = 471,
+        eCSSPropertyAlias__webkit_perspective = 472,
+        eCSSPropertyAlias__webkit_perspective_origin = 473,
+        eCSSPropertyAlias__webkit_text_size_adjust = 474,
+        eCSSPropertyAlias__webkit_transform = 475,
+        eCSSPropertyAlias__webkit_transform_origin = 476,
+        eCSSPropertyAlias__webkit_transform_style = 477,
+        eCSSPropertyAlias__webkit_transition = 478,
+        eCSSPropertyAlias__webkit_transition_delay = 479,
+        eCSSPropertyAlias__webkit_transition_duration = 480,
+        eCSSPropertyAlias__webkit_transition_property = 481,
+        eCSSPropertyAlias__webkit_transition_timing_function = 482,
+        eCSSPropertyAlias__webkit_user_select = 483,
+        eCSSPropertyAlias_word_wrap = 484,
         eCSSPropertyExtra_no_properties = 485,
         eCSSPropertyExtra_all_properties = 486,
-        eCSSPropertyExtra_x_none_value = 487,
-        eCSSPropertyExtra_x_auto_value = 488,
-        eCSSPropertyExtra_variable = 489,
-        eCSSProperty_DOM = 490,
+        eCSSPropertyExtra_variable = 487,
     }
     #[repr(i32)]
     #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
diff --git a/components/style/gecko/rules.rs b/components/style/gecko/rules.rs
index 2f144279656..a57314a418c 100644
--- a/components/style/gecko/rules.rs
+++ b/components/style/gecko/rules.rs
@@ -5,17 +5,18 @@
 //! Bindings for CSS Rule objects
 
 use byteorder::{BigEndian, WriteBytesExt};
-use computed_values::{font_stretch, font_style, font_weight};
 use counter_style::{self, CounterBound};
 use cssparser::UnicodeRange;
-use font_face::{FontDisplay, FontWeight, Source};
+use font_face::{FontDisplay, FontWeight, FontStretch, FontStyle, Source};
 use gecko_bindings::structs::{self, nsCSSValue};
 use gecko_bindings::sugar::ns_css_value::ToNsCssValue;
 use properties::longhands::font_language_override;
 use std::str;
 use values::computed::font::FamilyName;
 use values::generics::font::FontTag;
+use values::specified::font::{AbsoluteFontWeight, FontStretch as SpecifiedFontStretch};
 use values::specified::font::{SpecifiedFontFeatureSettings, SpecifiedFontVariationSettings};
+use values::specified::font::SpecifiedFontStyle;
 
 impl<'a> ToNsCssValue for &'a FamilyName {
     fn convert(self, nscssvalue: &mut nsCSSValue) {
@@ -23,19 +24,20 @@ impl<'a> ToNsCssValue for &'a FamilyName {
     }
 }
 
-impl ToNsCssValue for font_weight::T {
+impl<'a> ToNsCssValue for &'a SpecifiedFontStretch {
     fn convert(self, nscssvalue: &mut nsCSSValue) {
-        nscssvalue.set_font_weight(self.0)
+        let number = match *self {
+            SpecifiedFontStretch::Stretch(ref p) => p.get(),
+            SpecifiedFontStretch::Keyword(ref kw) => kw.compute().0,
+            SpecifiedFontStretch::System(..) => unreachable!(),
+        };
+        nscssvalue.set_font_stretch(number);
     }
 }
 
-impl<'a> ToNsCssValue for &'a FontWeight {
+impl<'a> ToNsCssValue for &'a AbsoluteFontWeight {
     fn convert(self, nscssvalue: &mut nsCSSValue) {
-        match *self {
-            FontWeight::Normal => nscssvalue.set_enum(structs::NS_FONT_WEIGHT_NORMAL as i32),
-            FontWeight::Bold => nscssvalue.set_enum(structs::NS_FONT_WEIGHT_BOLD as i32),
-            FontWeight::Weight(weight) => nscssvalue.set_font_weight(weight.0),
-        }
+        nscssvalue.set_font_weight(self.compute().0)
     }
 }
 
@@ -77,6 +79,52 @@ impl<'a> ToNsCssValue for &'a SpecifiedFontVariationSettings {
     }
 }
 
+macro_rules! descriptor_range_conversion {
+    ($name:ident) => {
+        impl<'a> ToNsCssValue for &'a $name {
+            fn convert(self, nscssvalue: &mut nsCSSValue) {
+                let $name(ref first, ref second) = *self;
+                let second = match *second {
+                    None => {
+                        nscssvalue.set_from(first);
+                        return;
+                    }
+                    Some(ref second) => second,
+                };
+
+                let mut a = nsCSSValue::null();
+                let mut b = nsCSSValue::null();
+
+                a.set_from(first);
+                b.set_from(second);
+
+                nscssvalue.set_pair(&a, &b);
+            }
+        }
+    }
+}
+
+descriptor_range_conversion!(FontWeight);
+descriptor_range_conversion!(FontStretch);
+
+impl<'a> ToNsCssValue for &'a FontStyle {
+    fn convert(self, nscssvalue: &mut nsCSSValue) {
+        match *self {
+            FontStyle::Normal => nscssvalue.set_normal(),
+            FontStyle::Italic => nscssvalue.set_enum(structs::NS_FONT_STYLE_ITALIC as i32),
+            FontStyle::Oblique(ref first, ref second) => {
+                let mut a = nsCSSValue::null();
+                let mut b = nsCSSValue::null();
+
+                a.set_font_style(SpecifiedFontStyle::compute_angle(first).degrees());
+                b.set_font_style(SpecifiedFontStyle::compute_angle(second).degrees());
+
+                nscssvalue.set_pair(&a, &b);
+            }
+        }
+    }
+}
+
 impl<'a> ToNsCssValue for &'a font_language_override::SpecifiedValue {
     fn convert(self, nscssvalue: &mut nsCSSValue) {
         match *self {
@@ -90,46 +138,6 @@ impl<'a> ToNsCssValue for &'a font_language_override::SpecifiedValue {
     }
 }
 
-macro_rules! map_enum {
-    (
-        $(
-            $prop:ident {
-                $($servo:ident => $gecko:ident,)+
-            }
-        )+
-    ) => {
-        $(
-            impl<'a> ToNsCssValue for &'a $prop::T {
-                fn convert(self, nscssvalue: &mut nsCSSValue) {
-                    nscssvalue.set_enum(match *self {
-                        $( $prop::T::$servo => structs::$gecko as i32, )+
-                    })
-                }
-            }
-        )+
-    }
-}
-
-map_enum! {
-    font_style {
-        Normal => NS_FONT_STYLE_NORMAL,
-        Italic => NS_FONT_STYLE_ITALIC,
-        Oblique => NS_FONT_STYLE_OBLIQUE,
-    }
-
-    font_stretch {
-        Normal          => NS_FONT_STRETCH_NORMAL,
-        UltraCondensed  => NS_FONT_STRETCH_ULTRA_CONDENSED,
-        ExtraCondensed  => NS_FONT_STRETCH_EXTRA_CONDENSED,
-        Condensed       => NS_FONT_STRETCH_CONDENSED,
-        SemiCondensed   => NS_FONT_STRETCH_SEMI_CONDENSED,
-        SemiExpanded    => NS_FONT_STRETCH_SEMI_EXPANDED,
-        Expanded        => NS_FONT_STRETCH_EXPANDED,
-        ExtraExpanded   => NS_FONT_STRETCH_EXTRA_EXPANDED,
-        UltraExpanded   => NS_FONT_STRETCH_ULTRA_EXPANDED,
-    }
-}
-
 impl<'a> ToNsCssValue for &'a Vec<Source> {
     fn convert(self, nscssvalue: &mut nsCSSValue) {
         let src_len = self.iter().fold(0, |acc, src| {
diff --git a/components/style/gecko_bindings/sugar/ns_css_value.rs b/components/style/gecko_bindings/sugar/ns_css_value.rs
index 45693561510..644166e3797 100644
--- a/components/style/gecko_bindings/sugar/ns_css_value.rs
+++ b/components/style/gecko_bindings/sugar/ns_css_value.rs
@@ -167,19 +167,29 @@ impl nsCSSValue {
         unsafe { bindings::Gecko_CSSValue_SetAtomIdent(self, s.into_addrefed()) }
     }
 
-    /// Set to a font format
+    /// Set to a font format.
     pub fn set_font_format(&mut self, s: &str) {
         self.set_string_internal(s, nsCSSUnit::eCSSUnit_Font_Format);
     }
 
-    /// Set to a local font value
+    /// Set to a local font value.
     pub fn set_local_font(&mut self, s: &Atom) {
         self.set_string_from_atom_internal(s, nsCSSUnit::eCSSUnit_Local_Font);
     }
 
+    /// Set to a font stretch.
+    pub fn set_font_stretch(&mut self, s: f32) {
+        unsafe { bindings::Gecko_CSSValue_SetFontStretch(self, s) }
+    }
+
+    /// Set to a font style
+    pub fn set_font_style(&mut self, s: f32) {
+        unsafe { bindings::Gecko_CSSValue_SetFontSlantStyle(self, s) }
+    }
+
     /// Set to a font weight
-    pub fn set_font_weight(&mut self, w: u16) {
-        unsafe { bindings::Gecko_CSSValue_SetFontWeight(self, w as f32) }
+    pub fn set_font_weight(&mut self, w: f32) {
+        unsafe { bindings::Gecko_CSSValue_SetFontWeight(self, w) }
     }
 
     fn set_int_internal(&mut self, value: i32, unit: nsCSSUnit) {
diff --git a/components/style/gecko_bindings/sugar/refptr.rs b/components/style/gecko_bindings/sugar/refptr.rs
index 0d8fb817a85..76a7021ef5b 100644
--- a/components/style/gecko_bindings/sugar/refptr.rs
+++ b/components/style/gecko_bindings/sugar/refptr.rs
@@ -312,3 +312,9 @@ impl_threadsafe_refcount!(
     Gecko_AddRefSharedFontListArbitraryThread,
     Gecko_ReleaseSharedFontListArbitraryThread
 );
+
+impl_threadsafe_refcount!(
+    ::gecko_bindings::structs::SheetLoadDataHolder,
+    Gecko_AddRefSheetLoadDataHolderArbitraryThread,
+    Gecko_ReleaseSheetLoadDataHolderArbitraryThread
+);
diff --git a/components/style/properties/build.py b/components/style/properties/build.py
index 326859ea6d8..04418723ee4 100644
--- a/components/style/properties/build.py
+++ b/components/style/properties/build.py
@@ -21,7 +21,7 @@ RE_PYTHON_ADDR = re.compile(r'<.+? object at 0x[0-9a-fA-F]+>')
 
 
 def main():
-    usage = "Usage: %s [ servo | gecko ] [ style-crate | html ]" % sys.argv[0]
+    usage = "Usage: %s [ servo | gecko ] [ style-crate | geckolib <template> | html ]" % sys.argv[0]
     if len(sys.argv) < 3:
         abort(usage)
     product = sys.argv[1]
@@ -39,6 +39,12 @@ def main():
             template = os.path.join(BASE, "gecko.mako.rs")
             rust = render(template, data=properties)
             write(os.environ["OUT_DIR"], "gecko_properties.rs", rust)
+    elif output == "geckolib":
+        if len(sys.argv) < 4:
+            abort(usage)
+        template = sys.argv[3]
+        header = render(template, data=properties)
+        sys.stdout.write(header)
     elif output == "html":
         write_html(properties)
 
diff --git a/components/style/properties/data.py b/components/style/properties/data.py
index 938b2c2c2bf..3ca9d347157 100644
--- a/components/style/properties/data.py
+++ b/components/style/properties/data.py
@@ -385,6 +385,7 @@ class Alias(object):
         self.name = name
         self.ident = to_rust_ident(name)
         self.camel_case = to_camel_case(self.ident)
+        self.original = original
         self.enabled_in = original.enabled_in
         self.servo_pref = original.servo_pref
         self.gecko_pref = gecko_pref
@@ -406,7 +407,7 @@ class Alias(object):
         return self.enabled_in == "content"
 
     def nscsspropertyid(self):
-        return "nsCSSPropertyID::eCSSPropertyAlias_%s" % self.camel_case
+        return "nsCSSPropertyID::eCSSPropertyAlias_%s" % self.ident
 
 
 class Method(object):
diff --git a/components/style/properties/gecko.mako.rs b/components/style/properties/gecko.mako.rs
index 067d014442d..a3d316df321 100644
--- a/components/style/properties/gecko.mako.rs
+++ b/components/style/properties/gecko.mako.rs
@@ -25,8 +25,6 @@ use gecko_bindings::bindings::Gecko_CopyFontFamilyFrom;
 use gecko_bindings::bindings::Gecko_CopyImageValueFrom;
 use gecko_bindings::bindings::Gecko_CopyListStyleImageFrom;
 use gecko_bindings::bindings::Gecko_EnsureImageLayersLength;
-use gecko_bindings::bindings::Gecko_FontWeight_SetFloat;
-use gecko_bindings::bindings::Gecko_FontWeight_ToFloat;
 use gecko_bindings::bindings::Gecko_SetCursorArrayLength;
 use gecko_bindings::bindings::Gecko_SetCursorImageValue;
 use gecko_bindings::bindings::Gecko_StyleTransition_SetUnsupportedProperty;
@@ -1806,7 +1804,7 @@ fn static_assert() {
     }
 
     pub fn set_computed_justify_items(&mut self, v: values::specified::JustifyItems) {
-        debug_assert_ne!(v.0, ::values::specified::align::AlignFlags::AUTO);
+        debug_assert_ne!(v.0, ::values::specified::align::AlignFlags::LEGACY);
         self.gecko.mJustifyItems = v.into();
     }
 
@@ -2601,15 +2599,49 @@ fn static_assert() {
     }
 
     pub fn set_font_weight(&mut self, v: longhands::font_weight::computed_value::T) {
-        unsafe { Gecko_FontWeight_SetFloat(&mut self.gecko.mFont.weight, v.0 as f32) };
+        unsafe { bindings::Gecko_FontWeight_SetFloat(&mut self.gecko.mFont.weight, v.0) };
     }
     ${impl_simple_copy('font_weight', 'mFont.weight')}
 
     pub fn clone_font_weight(&self) -> longhands::font_weight::computed_value::T {
-        let weight: f32 = unsafe { Gecko_FontWeight_ToFloat(self.gecko.mFont.weight) };
-        debug_assert!(weight >= 0.0 &&
-                      weight <= ::std::u16::MAX as f32);
-        longhands::font_weight::computed_value::T(weight as u16)
+        let weight: f32 = unsafe {
+            bindings::Gecko_FontWeight_ToFloat(self.gecko.mFont.weight)
+        };
+        longhands::font_weight::computed_value::T(weight)
+    }
+
+    pub fn set_font_stretch(&mut self, v: longhands::font_stretch::computed_value::T) {
+        unsafe { bindings::Gecko_FontStretch_SetFloat(&mut self.gecko.mFont.stretch, (v.0).0) };
+    }
+    ${impl_simple_copy('font_stretch', 'mFont.stretch')}
+    pub fn clone_font_stretch(&self) -> longhands::font_stretch::computed_value::T {
+        use values::computed::Percentage;
+        use values::generics::NonNegative;
+
+        let stretch =
+            unsafe { bindings::Gecko_FontStretch_ToFloat(self.gecko.mFont.stretch) };
+        debug_assert!(stretch >= 0.);
+
+        NonNegative(Percentage(stretch))
+    }
+
+    pub fn set_font_style(&mut self, v: longhands::font_style::computed_value::T) {
+        use values::generics::font::FontStyle;
+        let s = &mut self.gecko.mFont.style;
+        unsafe {
+            match v {
+                FontStyle::Normal => bindings::Gecko_FontSlantStyle_SetNormal(s),
+                FontStyle::Italic => bindings::Gecko_FontSlantStyle_SetItalic(s),
+                FontStyle::Oblique(ref angle) => {
+                    bindings::Gecko_FontSlantStyle_SetOblique(s, angle.0.degrees())
+                }
+            }
+        }
+    }
+    ${impl_simple_copy('font_style', 'mFont.style')}
+    pub fn clone_font_style(&self) -> longhands::font_style::computed_value::T {
+        use values::computed::font::FontStyle;
+        FontStyle::from_gecko(self.gecko.mFont.style)
     }
 
     ${impl_simple_type_with_conversion("font_synthesis", "mFont.synthesis")}
diff --git a/components/style/properties/helpers/animated_properties.mako.rs b/components/style/properties/helpers/animated_properties.mako.rs
index a06d9f62f71..e2d15139128 100644
--- a/components/style/properties/helpers/animated_properties.mako.rs
+++ b/components/style/properties/helpers/animated_properties.mako.rs
@@ -19,7 +19,6 @@ use num_traits::Zero;
 use properties::{CSSWideKeyword, PropertyDeclaration};
 use properties::longhands;
 use properties::longhands::font_weight::computed_value::T as FontWeight;
-use properties::longhands::font_stretch::computed_value::T as FontStretch;
 use properties::longhands::visibility::computed_value::T as Visibility;
 use properties::PropertyId;
 use properties::{LonghandId, ShorthandId};
@@ -873,20 +872,6 @@ impl ToAnimatedZero for MaxLength {
     fn to_animated_zero(&self) -> Result<Self, ()> { Err(()) }
 }
 
-/// <http://dev.w3.org/csswg/css-transitions/#animtype-font-weight>
-impl Animate for FontWeight {
-    #[inline]
-    fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
-        let a = self.0 as f64;
-        let b = other.0 as f64;
-        const NORMAL: f64 = 400.;
-        let (this_weight, other_weight) = procedure.weights();
-        let weight = (a - NORMAL) * this_weight + (b - NORMAL) * other_weight + NORMAL;
-        let weight = (weight.max(100.).min(900.) / 100.).round() * 100.;
-        Ok(FontWeight(weight as u16))
-    }
-}
-
 impl ToAnimatedZero for FontWeight {
     #[inline]
     fn to_animated_zero(&self) -> Result<Self, ()> {
@@ -894,62 +879,6 @@ impl ToAnimatedZero for FontWeight {
     }
 }
 
-/// <https://drafts.csswg.org/css-fonts/#font-stretch-prop>
-impl Animate for FontStretch {
-    #[inline]
-    fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()>
-    {
-        let from = f64::from(*self);
-        let to = f64::from(*other);
-        let normal = f64::from(FontStretch::Normal);
-        let (this_weight, other_weight) = procedure.weights();
-        let result = (from - normal) * this_weight + (to - normal) * other_weight + normal;
-        Ok(result.into())
-    }
-}
-
-impl ComputeSquaredDistance for FontStretch {
-    #[inline]
-    fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()> {
-        f64::from(*self).compute_squared_distance(&(*other).into())
-    }
-}
-
-impl ToAnimatedZero for FontStretch {
-    #[inline]
-    fn to_animated_zero(&self) -> Result<Self, ()> { Err(()) }
-}
-
-/// We should treat font stretch as real number in order to interpolate this property.
-/// <https://drafts.csswg.org/css-fonts-3/#font-stretch-animation>
-impl From<FontStretch> for f64 {
-    fn from(stretch: FontStretch) -> f64 {
-        use self::FontStretch::*;
-        match stretch {
-            UltraCondensed => 1.0,
-            ExtraCondensed => 2.0,
-            Condensed => 3.0,
-            SemiCondensed => 4.0,
-            Normal => 5.0,
-            SemiExpanded => 6.0,
-            Expanded => 7.0,
-            ExtraExpanded => 8.0,
-            UltraExpanded => 9.0,
-        }
-    }
-}
-
-impl Into<FontStretch> for f64 {
-    fn into(self) -> FontStretch {
-        use properties::longhands::font_stretch::computed_value::T::*;
-        let index = (self + 0.5).floor().min(9.0).max(1.0);
-        static FONT_STRETCH_ENUM_MAP: [FontStretch; 9] =
-            [ UltraCondensed, ExtraCondensed, Condensed, SemiCondensed, Normal,
-              SemiExpanded, Expanded, ExtraExpanded, UltraExpanded ];
-        FONT_STRETCH_ENUM_MAP[(index - 1.0) as usize]
-    }
-}
-
 /// <https://drafts.csswg.org/css-fonts-4/#font-variation-settings-def>
 impl Animate for FontVariationSettings {
     #[inline]
diff --git a/components/style/properties/longhand/border.mako.rs b/components/style/properties/longhand/border.mako.rs
index bf2e8e9210b..9bb3dbcec28 100644
--- a/components/style/properties/longhand/border.mako.rs
+++ b/components/style/properties/longhand/border.mako.rs
@@ -43,17 +43,19 @@
         needs_context=False,
     )}
 
-    ${helpers.predefined_type("border-%s-width" % side_name,
-                              "BorderSideWidth",
-                              "::values::computed::NonNegativeLength::new(3.)",
-                              computed_type="::values::computed::NonNegativeLength",
-                              alias=maybe_moz_logical_alias(product, side, "-moz-border-%s-width"),
-                              spec=maybe_logical_spec(side, "width"),
-                              animation_value_type="NonNegativeLength",
-                              logical=is_logical,
-                              flags="APPLIES_TO_FIRST_LETTER",
-                              allow_quirks=not is_logical,
-                              servo_restyle_damage = "reflow rebuild_and_reflow_inline")}
+    ${helpers.predefined_type(
+        "border-%s-width" % side_name,
+        "BorderSideWidth",
+        "::values::computed::NonNegativeLength::new(3.)",
+        computed_type="::values::computed::NonNegativeLength",
+        alias=maybe_moz_logical_alias(product, side, "-moz-border-%s-width"),
+        spec=maybe_logical_spec(side, "width"),
+        animation_value_type="NonNegativeLength",
+        logical=is_logical,
+        flags="APPLIES_TO_FIRST_LETTER GETCS_NEEDS_LAYOUT_FLUSH",
+        allow_quirks=not is_logical,
+        servo_restyle_damage="reflow rebuild_and_reflow_inline"
+    )}
 % endfor
 
 ${helpers.gecko_keyword_conversion(Keyword('border-style',
diff --git a/components/style/properties/longhand/box.mako.rs b/components/style/properties/longhand/box.mako.rs
index f671144b126..806afcbd1b6 100644
--- a/components/style/properties/longhand/box.mako.rs
+++ b/components/style/properties/longhand/box.mako.rs
@@ -403,14 +403,18 @@ ${helpers.predefined_type(
 
 <% transform_extra_prefixes = "moz:layout.css.prefixes.transforms webkit" %>
 
-${helpers.predefined_type("transform", "Transform",
-                          "generics::transform::Transform::none()",
-                          extra_prefixes=transform_extra_prefixes,
-                          animation_value_type="ComputedValue",
-                          gecko_ffi_name="mSpecifiedTransform",
-                          flags="CREATES_STACKING_CONTEXT FIXPOS_CB",
-                          spec="https://drafts.csswg.org/css-transforms/#propdef-transform",
-                          servo_restyle_damage = "reflow_out_of_flow")}
+${helpers.predefined_type(
+    "transform",
+    "Transform",
+    "generics::transform::Transform::none()",
+    extra_prefixes=transform_extra_prefixes,
+    animation_value_type="ComputedValue",
+    gecko_ffi_name="mSpecifiedTransform",
+    flags="CREATES_STACKING_CONTEXT FIXPOS_CB \
+           GETCS_NEEDS_LAYOUT_FLUSH CAN_ANIMATE_ON_COMPOSITOR",
+    spec="https://drafts.csswg.org/css-transforms/#propdef-transform",
+    servo_restyle_damage="reflow_out_of_flow"
+)}
 
 ${helpers.predefined_type("rotate", "Rotate",
                           "generics::transform::Rotate::None",
@@ -430,14 +434,17 @@ ${helpers.predefined_type("scale", "Scale",
                           spec="https://drafts.csswg.org/css-transforms-2/#individual-transforms",
                           servo_restyle_damage = "reflow_out_of_flow")}
 
-${helpers.predefined_type("translate", "Translate",
-                          "generics::transform::Translate::None",
-                          animation_value_type="ComputedValue",
-                          boxed=True,
-                          flags="CREATES_STACKING_CONTEXT FIXPOS_CB",
-                          gecko_pref="layout.css.individual-transform.enabled",
-                          spec="https://drafts.csswg.org/css-transforms-2/#individual-transforms",
-                          servo_restyle_damage = "reflow_out_of_flow")}
+${helpers.predefined_type(
+    "translate",
+    "Translate",
+    "generics::transform::Translate::None",
+    animation_value_type="ComputedValue",
+    boxed=True,
+    flags="CREATES_STACKING_CONTEXT FIXPOS_CB GETCS_NEEDS_LAYOUT_FLUSH",
+    gecko_pref="layout.css.individual-transform.enabled",
+    spec="https://drafts.csswg.org/css-transforms-2/#individual-transforms",
+    servo_restyle_damage="reflow_out_of_flow"
+)}
 
 // CSSOM View Module
 // https://www.w3.org/TR/cssom-view-1/
@@ -529,14 +536,17 @@ ${helpers.predefined_type(
     servo_restyle_damage = "reflow_out_of_flow",
 )}
 
-${helpers.predefined_type("perspective-origin",
-                          "position::Position",
-                          "computed::position::Position::center()",
-                          boxed=True,
-                          extra_prefixes=transform_extra_prefixes,
-                          spec="https://drafts.csswg.org/css-transforms-2/#perspective-origin-property",
-                          animation_value_type="ComputedValue",
-                          servo_restyle_damage = "reflow_out_of_flow")}
+${helpers.predefined_type(
+    "perspective-origin",
+    "position::Position",
+    "computed::position::Position::center()",
+    boxed=True,
+    extra_prefixes=transform_extra_prefixes,
+    spec="https://drafts.csswg.org/css-transforms-2/#perspective-origin-property",
+    flags="GETCS_NEEDS_LAYOUT_FLUSH",
+    animation_value_type="ComputedValue",
+    servo_restyle_damage="reflow_out_of_flow"
+)}
 
 ${helpers.single_keyword("backface-visibility",
                          "visible hidden",
@@ -565,15 +575,18 @@ ${helpers.predefined_type(
     servo_restyle_damage = "reflow_out_of_flow",
 )}
 
-${helpers.predefined_type("transform-origin",
-                          "TransformOrigin",
-                          "computed::TransformOrigin::initial_value()",
-                          animation_value_type="ComputedValue",
-                          extra_prefixes=transform_extra_prefixes,
-                          gecko_ffi_name="mTransformOrigin",
-                          boxed=True,
-                          spec="https://drafts.csswg.org/css-transforms/#transform-origin-property",
-                          servo_restyle_damage = "reflow_out_of_flow")}
+${helpers.predefined_type(
+    "transform-origin",
+    "TransformOrigin",
+    "computed::TransformOrigin::initial_value()",
+    animation_value_type="ComputedValue",
+    extra_prefixes=transform_extra_prefixes,
+    gecko_ffi_name="mTransformOrigin",
+    boxed=True,
+    flags="GETCS_NEEDS_LAYOUT_FLUSH",
+    spec="https://drafts.csswg.org/css-transforms/#transform-origin-property",
+    servo_restyle_damage="reflow_out_of_flow"
+)}
 
 ${helpers.predefined_type("contain",
                           "Contain",
diff --git a/components/style/properties/longhand/column.mako.rs b/components/style/properties/longhand/column.mako.rs
index 3b2a3ec38ed..7a97c3f41e3 100644
--- a/components/style/properties/longhand/column.mako.rs
+++ b/components/style/properties/longhand/column.mako.rs
@@ -31,17 +31,6 @@ ${helpers.predefined_type(
 
 
 
-${helpers.predefined_type(
-    "column-gap",
-    "length::NonNegativeLengthOrPercentageOrNormal",
-    "Either::Second(Normal)",
-    extra_prefixes="moz",
-    servo_pref="layout.columns.enabled",
-    animation_value_type="NonNegativeLengthOrPercentageOrNormal",
-    spec="https://drafts.csswg.org/css-multicol/#propdef-column-gap",
-    servo_restyle_damage = "reflow",
-)}
-
 ${helpers.single_keyword("column-fill", "balance auto", extra_prefixes="moz",
                          products="gecko", animation_value_type="discrete",
                          spec="https://drafts.csswg.org/css-multicol/#propdef-column-fill")}
diff --git a/components/style/properties/longhand/effects.mako.rs b/components/style/properties/longhand/effects.mako.rs
index 3292e1bf36c..30493bd270d 100644
--- a/components/style/properties/longhand/effects.mako.rs
+++ b/components/style/properties/longhand/effects.mako.rs
@@ -7,13 +7,16 @@
 // Box-shadow, etc.
 <% data.new_style_struct("Effects", inherited=False) %>
 
-${helpers.predefined_type("opacity",
-                          "Opacity",
-                          "1.0",
-                          animation_value_type="ComputedValue",
-                          flags="CREATES_STACKING_CONTEXT APPLIES_TO_PLACEHOLDER",
-                          spec="https://drafts.csswg.org/css-color/#opacity",
-                          servo_restyle_damage = "reflow_out_of_flow")}
+${helpers.predefined_type(
+    "opacity",
+    "Opacity",
+    "1.0",
+    animation_value_type="ComputedValue",
+    flags="CREATES_STACKING_CONTEXT APPLIES_TO_PLACEHOLDER \
+           CAN_ANIMATE_ON_COMPOSITOR",
+    spec="https://drafts.csswg.org/css-color/#opacity",
+    servo_restyle_damage = "reflow_out_of_flow"
+)}
 
 ${helpers.predefined_type(
     "box-shadow",
diff --git a/components/style/properties/longhand/font.mako.rs b/components/style/properties/longhand/font.mako.rs
index 0d246d3b358..0477a2cd0d5 100644
--- a/components/style/properties/longhand/font.mako.rs
+++ b/components/style/properties/longhand/font.mako.rs
@@ -15,15 +15,15 @@ ${helpers.predefined_type("font-family",
                           spec="https://drafts.csswg.org/css-fonts/#propdef-font-family",
                           servo_restyle_damage="rebuild_and_reflow")}
 
-${helpers.single_keyword_system(
+${helpers.predefined_type(
     "font-style",
-    "normal italic oblique",
-    gecko_constant_prefix="NS_FONT_STYLE",
-    gecko_ffi_name="mFont.style",
-    spec="https://drafts.csswg.org/css-fonts/#propdef-font-style",
+    "FontStyle",
+    initial_value="computed::FontStyle::normal()",
+    initial_specified_value="specified::FontStyle::normal()",
+    animation_value_type="FontStyle",
     flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
-    animation_value_type="discrete",
-    servo_restyle_damage="rebuild_and_reflow"
+    spec="https://drafts.csswg.org/css-fonts/#propdef-font-style",
+    servo_restyle_damage="rebuild_and_reflow",
 )}
 
 <% font_variant_caps_custom_consts= { "small-caps": "SMALLCAPS",
@@ -43,14 +43,16 @@ ${helpers.single_keyword_system("font-variant-caps",
                                 animation_value_type="discrete",
                                 servo_restyle_damage="rebuild_and_reflow")}
 
-${helpers.predefined_type("font-weight",
-                          "FontWeight",
-                          initial_value="computed::FontWeight::normal()",
-                          initial_specified_value="specified::FontWeight::Normal",
-                          animation_value_type="ComputedValue",
-                          flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
-                          spec="https://drafts.csswg.org/css-fonts/#propdef-font-weight",
-                          servo_restyle_damage="rebuild_and_reflow")}
+${helpers.predefined_type(
+    "font-weight",
+    "FontWeight",
+    initial_value="computed::FontWeight::normal()",
+    initial_specified_value="specified::FontWeight::normal()",
+    animation_value_type="Number",
+    flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
+    spec="https://drafts.csswg.org/css-fonts/#propdef-font-weight",
+    servo_restyle_damage="rebuild_and_reflow",
+)}
 
 ${helpers.predefined_type("font-size",
                           "FontSize",
@@ -79,17 +81,16 @@ ${helpers.predefined_type("font-synthesis",
                           flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
                           spec="https://drafts.csswg.org/css-fonts/#propdef-font-synthesis")}
 
-${helpers.single_keyword_system("font-stretch",
-                                "normal ultra-condensed extra-condensed condensed \
-                                 semi-condensed semi-expanded expanded extra-expanded \
-                                 ultra-expanded",
-                                gecko_ffi_name="mFont.stretch",
-                                gecko_constant_prefix="NS_FONT_STRETCH",
-                                cast_type='i16',
-                                spec="https://drafts.csswg.org/css-fonts/#propdef-font-stretch",
-                                flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
-                                animation_value_type="ComputedValue",
-                                servo_restyle_damage="rebuild_and_reflow")}
+${helpers.predefined_type(
+    "font-stretch",
+    "FontStretch",
+    initial_value="computed::NonNegativePercentage::hundred()",
+    initial_specified_value="specified::FontStretch::normal()",
+    animation_value_type="Percentage",
+    flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
+    spec="https://drafts.csswg.org/css-fonts/#propdef-font-stretch",
+    servo_restyle_damage="rebuild_and_reflow",
+)}
 
 ${helpers.single_keyword_system("font-kerning",
                                 "auto none normal",
@@ -288,12 +289,11 @@ ${helpers.predefined_type("-x-text-zoom",
                               -moz-window -moz-document -moz-workspace -moz-desktop
                               -moz-info -moz-dialog -moz-button -moz-pull-down-menu
                               -moz-list -moz-field""".split()
-            kw_font_props = """font_style font_variant_caps font_stretch
+            kw_font_props = """font_variant_caps
                                font_kerning font_variant_position font_variant_ligatures
                                font_variant_east_asian font_variant_numeric
                                font_optical_sizing""".split()
-            kw_cast = """font_style font_variant_caps font_stretch
-                         font_kerning font_variant_position
+            kw_cast = """font_variant_caps font_kerning font_variant_position
                          font_optical_sizing""".split()
         %>
         #[derive(Clone, Copy, Debug, Eq, Hash, MallocSizeOf, PartialEq, ToCss)]
@@ -328,7 +328,9 @@ ${helpers.predefined_type("-x-text-zoom",
                 use gecko_bindings::bindings;
                 use gecko_bindings::structs::{LookAndFeel_FontID, nsFont};
                 use std::mem;
-                use values::computed::font::{FontSize, FontFamilyList};
+                use values::computed::Percentage;
+                use values::computed::font::{FontSize, FontStyle, FontFamilyList};
+                use values::generics::NonNegative;
 
                 let id = match *self {
                     % for font in system_fonts:
@@ -347,7 +349,11 @@ ${helpers.predefined_type("-x-text-zoom",
                         cx.device().pres_context()
                     )
                 }
-                let weight = longhands::font_weight::computed_value::T::from_gecko_weight(system.weight);
+                let font_weight = longhands::font_weight::computed_value::T::from_gecko_weight(system.weight);
+                let font_stretch = NonNegative(Percentage(unsafe {
+                    bindings::Gecko_FontStretch_ToFloat(system.stretch)
+                }));
+                let font_style = FontStyle::from_gecko(system.style);
                 let ret = ComputedSystemFont {
                     font_family: longhands::font_family::computed_value::T(
                         FontFamilyList(
@@ -355,10 +361,12 @@ ${helpers.predefined_type("-x-text-zoom",
                         )
                     ),
                     font_size: FontSize {
-                            size: Au(system.size).into(),
-                            keyword_info: None
+                        size: Au(system.size).into(),
+                        keyword_info: None
                     },
-                    font_weight: weight,
+                    font_weight,
+                    font_stretch,
+                    font_style,
                     font_size_adjust: longhands::font_size_adjust::computed_value
                                                ::T::from_gecko_adjust(system.sizeAdjust),
                     % for kwprop in kw_font_props:
diff --git a/components/style/properties/longhand/inherited_text.mako.rs b/components/style/properties/longhand/inherited_text.mako.rs
index 99efd55c60f..abf1054675c 100644
--- a/components/style/properties/longhand/inherited_text.mako.rs
+++ b/components/style/properties/longhand/inherited_text.mako.rs
@@ -6,13 +6,16 @@
 <% from data import Keyword %>
 <% data.new_style_struct("InheritedText", inherited=True, gecko_name="Text") %>
 
-${helpers.predefined_type("line-height",
-                          "LineHeight",
-                          "computed::LineHeight::normal()",
-                          animation_value_type="LineHeight",
-                          flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE APPLIES_TO_PLACEHOLDER",
-                          spec="https://drafts.csswg.org/css2/visudet.html#propdef-line-height",
-                          servo_restyle_damage = "reflow")}
+${helpers.predefined_type(
+    "line-height",
+    "LineHeight",
+    "computed::LineHeight::normal()",
+    animation_value_type="LineHeight",
+    flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_FIRST_LINE \
+           APPLIES_TO_PLACEHOLDER GETCS_NEEDS_LAYOUT_FLUSH",
+    spec="https://drafts.csswg.org/css2/visudet.html#propdef-line-height",
+    servo_restyle_damage="reflow"
+)}
 
 // CSS Text Module Level 3
 
diff --git a/components/style/properties/longhand/margin.mako.rs b/components/style/properties/longhand/margin.mako.rs
index 5c0d06f8206..1a964bcbb74 100644
--- a/components/style/properties/longhand/margin.mako.rs
+++ b/components/style/properties/longhand/margin.mako.rs
@@ -12,12 +12,17 @@
         if side[1]:
             spec = "https://drafts.csswg.org/css-logical-props/#propdef-margin-%s" % side[1]
     %>
-    ${helpers.predefined_type("margin-%s" % side[0], "LengthOrPercentageOrAuto",
-                              "computed::LengthOrPercentageOrAuto::Length(computed::Length::new(0.))",
-                              alias=maybe_moz_logical_alias(product, side, "-moz-margin-%s"),
-                              allow_quirks=not side[1],
-                              animation_value_type="ComputedValue", logical = side[1], spec = spec,
-                              flags="APPLIES_TO_FIRST_LETTER",
-                              allowed_in_page_rule=True,
-                              servo_restyle_damage = "reflow")}
+    ${helpers.predefined_type(
+        "margin-%s" % side[0],
+        "LengthOrPercentageOrAuto",
+        "computed::LengthOrPercentageOrAuto::Length(computed::Length::new(0.))",
+        alias=maybe_moz_logical_alias(product, side, "-moz-margin-%s"),
+        allow_quirks=not side[1],
+        animation_value_type="ComputedValue",
+        logical=side[1],
+        spec=spec,
+        flags="APPLIES_TO_FIRST_LETTER GETCS_NEEDS_LAYOUT_FLUSH",
+        allowed_in_page_rule=True,
+        servo_restyle_damage="reflow"
+    )}
 % endfor
diff --git a/components/style/properties/longhand/padding.mako.rs b/components/style/properties/longhand/padding.mako.rs
index be0f9553cd2..3d2467c0ca0 100644
--- a/components/style/properties/longhand/padding.mako.rs
+++ b/components/style/properties/longhand/padding.mako.rs
@@ -14,13 +14,16 @@
         if side[1]:
             spec = "https://drafts.csswg.org/css-logical-props/#propdef-padding-%s" % side[1]
     %>
-    ${helpers.predefined_type("padding-%s" % side[0], "NonNegativeLengthOrPercentage",
-                              "computed::NonNegativeLengthOrPercentage::zero()",
-                              alias=maybe_moz_logical_alias(product, side, "-moz-padding-%s"),
-                              animation_value_type="NonNegativeLengthOrPercentage",
-                              logical = side[1],
-                              spec = spec,
-                              flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_PLACEHOLDER",
-                              allow_quirks=not side[1],
-                              servo_restyle_damage = "reflow rebuild_and_reflow_inline")}
+    ${helpers.predefined_type(
+        "padding-%s" % side[0],
+        "NonNegativeLengthOrPercentage",
+        "computed::NonNegativeLengthOrPercentage::zero()",
+        alias=maybe_moz_logical_alias(product, side, "-moz-padding-%s"),
+        animation_value_type="NonNegativeLengthOrPercentage",
+        logical=side[1],
+        spec=spec,
+        flags="APPLIES_TO_FIRST_LETTER APPLIES_TO_PLACEHOLDER GETCS_NEEDS_LAYOUT_FLUSH",
+        allow_quirks=not side[1],
+        servo_restyle_damage="reflow rebuild_and_reflow_inline"
+    )}
 % endfor
diff --git a/components/style/properties/longhand/position.mako.rs b/components/style/properties/longhand/position.mako.rs
index 5d64159654c..a99cebfdba9 100644
--- a/components/style/properties/longhand/position.mako.rs
+++ b/components/style/properties/longhand/position.mako.rs
@@ -10,18 +10,28 @@
 
 // "top" / "left" / "bottom" / "right"
 % for side in PHYSICAL_SIDES:
-    ${helpers.predefined_type(side, "LengthOrPercentageOrAuto",
-                              "computed::LengthOrPercentageOrAuto::Auto",
-                              spec="https://www.w3.org/TR/CSS2/visuren.html#propdef-%s" % side,
-                              animation_value_type="ComputedValue",
-                              allow_quirks=True, servo_restyle_damage = "reflow_out_of_flow")}
+    ${helpers.predefined_type(
+        side,
+        "LengthOrPercentageOrAuto",
+        "computed::LengthOrPercentageOrAuto::Auto",
+        spec="https://www.w3.org/TR/CSS2/visuren.html#propdef-%s" % side,
+        flags="GETCS_NEEDS_LAYOUT_FLUSH",
+        animation_value_type="ComputedValue",
+        allow_quirks=True,
+        servo_restyle_damage="reflow_out_of_flow"
+    )}
 % endfor
 // offset-* logical properties, map to "top" / "left" / "bottom" / "right"
 % for side in LOGICAL_SIDES:
-    ${helpers.predefined_type("offset-%s" % side, "LengthOrPercentageOrAuto",
-                              "computed::LengthOrPercentageOrAuto::Auto",
-                              spec="https://drafts.csswg.org/css-logical-props/#propdef-offset-%s" % side,
-                              animation_value_type="ComputedValue", logical=True)}
+    ${helpers.predefined_type(
+        "offset-%s" % side,
+        "LengthOrPercentageOrAuto",
+        "computed::LengthOrPercentageOrAuto::Auto",
+        spec="https://drafts.csswg.org/css-logical-props/#propdef-offset-%s" % side,
+        flags="GETCS_NEEDS_LAYOUT_FLUSH",
+        animation_value_type="ComputedValue",
+        logical=True,
+    )}
 % endfor
 
 #[cfg(feature = "gecko")]
@@ -118,11 +128,13 @@ ${helpers.single_keyword("flex-wrap", "nowrap wrap wrap-reverse",
     #[cfg(feature = "gecko")]
     impl_align_conversions!(::values::specified::align::AlignItems);
 
-    ${helpers.predefined_type(name="justify-items",
-                              type="JustifyItems",
-                              initial_value="computed::JustifyItems::auto()",
-                              spec="https://drafts.csswg.org/css-align/#propdef-justify-items",
-                              animation_value_type="discrete")}
+    ${helpers.predefined_type(
+        name="justify-items",
+        type="JustifyItems",
+        initial_value="computed::JustifyItems::legacy()",
+        spec="https://drafts.csswg.org/css-align/#propdef-justify-items",
+        animation_value_type="discrete",
+    )}
 
     #[cfg(feature = "gecko")]
     impl_align_conversions!(::values::specified::align::JustifyItems);
@@ -211,7 +223,8 @@ ${helpers.predefined_type(
             allow_quirks=not logical,
             spec=spec % size,
             animation_value_type="MozLength",
-            servo_restyle_damage = "reflow"
+            flags="GETCS_NEEDS_LAYOUT_FLUSH",
+            servo_restyle_damage="reflow"
         )}
         // min-width, min-height, min-block-size, min-inline-size,
         ${helpers.predefined_type(
@@ -289,13 +302,6 @@ ${helpers.predefined_type("object-position",
                           animation_value_type="ComputedValue")}
 
 % for kind in ["row", "column"]:
-    ${helpers.predefined_type("grid-%s-gap" % kind,
-                              "NonNegativeLengthOrPercentage",
-                              "computed::NonNegativeLengthOrPercentage::zero()",
-                              spec="https://drafts.csswg.org/css-grid/#propdef-grid-%s-gap" % kind,
-                              animation_value_type="NonNegativeLengthOrPercentage",
-                              products="gecko")}
-
     % for range in ["start", "end"]:
         ${helpers.predefined_type("grid-%s-%s" % (kind, range),
                                   "GridLine",
@@ -316,13 +322,16 @@ ${helpers.predefined_type("object-position",
                               products="gecko",
                               boxed=True)}
 
-    ${helpers.predefined_type("grid-template-%ss" % kind,
-                              "GridTemplateComponent",
-                              "specified::GenericGridTemplateComponent::None",
-                              products="gecko",
-                              spec="https://drafts.csswg.org/css-grid/#propdef-grid-template-%ss" % kind,
-                              boxed=True,
-                              animation_value_type="discrete")}
+    ${helpers.predefined_type(
+        "grid-template-%ss" % kind,
+        "GridTemplateComponent",
+        "specified::GenericGridTemplateComponent::None",
+        products="gecko",
+        spec="https://drafts.csswg.org/css-grid/#propdef-grid-template-%ss" % kind,
+        boxed=True,
+        flags="GETCS_NEEDS_LAYOUT_FLUSH",
+        animation_value_type="discrete"
+    )}
 
 % endfor
 
@@ -339,3 +348,23 @@ ${helpers.predefined_type("grid-template-areas",
                           products="gecko",
                           animation_value_type="discrete",
                           spec="https://drafts.csswg.org/css-grid/#propdef-grid-template-areas")}
+
+${helpers.predefined_type("column-gap",
+                          "length::NonNegativeLengthOrPercentageOrNormal",
+                          "Either::Second(Normal)",
+                          alias="grid-column-gap" if product == "gecko" else "",
+                          extra_prefixes="moz",
+                          servo_pref="layout.columns.enabled",
+                          spec="https://drafts.csswg.org/css-align-3/#propdef-column-gap",
+                          animation_value_type="NonNegativeLengthOrPercentageOrNormal",
+                          servo_restyle_damage = "reflow")}
+
+// no need for -moz- prefixed alias for this property
+${helpers.predefined_type("row-gap",
+                          "length::NonNegativeLengthOrPercentageOrNormal",
+                          "Either::Second(Normal)",
+                          alias="grid-row-gap",
+                          products="gecko",
+                          spec="https://drafts.csswg.org/css-align-3/#propdef-row-gap",
+                          animation_value_type="NonNegativeLengthOrPercentageOrNormal",
+                          servo_restyle_damage = "reflow")}
diff --git a/components/style/properties/longhand/ui.mako.rs b/components/style/properties/longhand/ui.mako.rs
index 5f2215760f8..683a8967ea3 100644
--- a/components/style/properties/longhand/ui.mako.rs
+++ b/components/style/properties/longhand/ui.mako.rs
@@ -41,28 +41,36 @@ ${helpers.single_keyword("-moz-window-shadow", "none default menu tooltip sheet"
                          enabled_in="chrome",
                          spec="None (Nonstandard internal property)")}
 
+// TODO(bug 1419695) This should be hidden from content.
 ${helpers.predefined_type("-moz-window-opacity", "Opacity", "1.0", products="gecko",
                           gecko_ffi_name="mWindowOpacity",
                           animation_value_type="ComputedValue",
-                          enabled_in="chrome",
                           spec="None (Nonstandard internal property)")}
 
-${helpers.predefined_type("-moz-window-transform", "Transform",
-                          "generics::transform::Transform::none()",
-                          products="gecko", gecko_ffi_name="mSpecifiedWindowTransform",
-                          animation_value_type="ComputedValue",
-                          enabled_in="chrome",
-                          spec="None (Nonstandard internal property)")}
+// TODO(bug 1419695) This should be hidden from content.
+${helpers.predefined_type(
+    "-moz-window-transform",
+    "Transform",
+    "generics::transform::Transform::none()",
+    products="gecko",
+    gecko_ffi_name="mSpecifiedWindowTransform",
+    flags="GETCS_NEEDS_LAYOUT_FLUSH",
+    animation_value_type="ComputedValue",
+    spec="None (Nonstandard internal property)"
+)}
 
-${helpers.predefined_type("-moz-window-transform-origin",
-                          "TransformOrigin",
-                          "computed::TransformOrigin::initial_value()",
-                          animation_value_type="ComputedValue",
-                          gecko_ffi_name="mWindowTransformOrigin",
-                          products="gecko",
-                          boxed=True,
-                          enabled_in="chrome",
-                          spec="None (Nonstandard internal property)")}
+// TODO(bug 1419695) This should be hidden from content.
+${helpers.predefined_type(
+    "-moz-window-transform-origin",
+    "TransformOrigin",
+    "computed::TransformOrigin::initial_value()",
+    animation_value_type="ComputedValue",
+    gecko_ffi_name="mWindowTransformOrigin",
+    products="gecko",
+    boxed=True,
+    flags="GETCS_NEEDS_LAYOUT_FLUSH",
+    spec="None (Nonstandard internal property)"
+)}
 
 // TODO(emilio): Probably also should be hidden from content.
 ${helpers.predefined_type("-moz-force-broken-image-icon",
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index a27a2d2e579..1042a5d1a4d 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -781,6 +781,15 @@ bitflags! {
         const APPLIES_TO_FIRST_LINE = 1 << 4;
         /// This longhand property applies to ::placeholder.
         const APPLIES_TO_PLACEHOLDER = 1 << 5;
+
+        /* The following flags are currently not used in Rust code, they
+         * only need to be listed in corresponding properties so that
+         * they can be checked in the C++ side via ServoCSSPropList.h. */
+        /// This property's getComputedStyle implementation requires layout
+        /// to be flushed.
+        const GETCS_NEEDS_LAYOUT_FLUSH = 0;
+        /// This property can be animated on the compositor.
+        const CAN_ANIMATE_ON_COMPOSITOR = 0;
     }
 }
 
@@ -2233,9 +2242,13 @@ pub mod style_structs {
                 pub fn compute_font_hash(&mut self) {
                     // Corresponds to the fields in
                     // `gfx::font_template::FontTemplateDescriptor`.
+                    //
+                    // FIXME(emilio): Where's font-style?
                     let mut hasher: FnvHasher = Default::default();
-                    hasher.write_u16(self.font_weight.0);
-                    self.font_stretch.hash(&mut hasher);
+                    // We hash the floating point number with four decimal
+                    // places.
+                    hasher.write_u64((self.font_weight.0 * 10000.).trunc() as u64);
+                    hasher.write_u64(((self.font_stretch.0).0 * 10000.).trunc() as u64);
                     self.font_family.hash(&mut hasher);
                     self.hash = hasher.finish()
                 }
diff --git a/components/style/properties/shorthand/font.mako.rs b/components/style/properties/shorthand/font.mako.rs
index cc3cd819cf2..5e14fd6ab50 100644
--- a/components/style/properties/shorthand/font.mako.rs
+++ b/components/style/properties/shorthand/font.mako.rs
@@ -27,6 +27,7 @@
     use properties::longhands::system_font::SystemFont;
     use values::specified::text::LineHeight;
     use values::specified::FontSize;
+    use values::specified::font::{FontStretch, FontStretchKeyword};
 
     <%
         gecko_sub_properties = "kerning language_override size_adjust \
@@ -94,8 +95,8 @@
                 }
             }
             if stretch.is_none() {
-                if let Ok(value) = input.try(|input| font_stretch::parse(context, input)) {
-                    stretch = Some(value);
+                if let Ok(value) = input.try(FontStretchKeyword::parse) {
+                    stretch = Some(FontStretch::Keyword(value));
                     continue
                 }
             }
@@ -180,15 +181,31 @@
             % endfor
             % endif
 
-            // In case of serialization for canvas font, we need to drop
-            // initial values of properties other than size and family.
-            % for name in "style variant_caps weight stretch".split():
+            // Only font-stretch keywords are allowed as part as the font
+            // shorthand.
+            let font_stretch = match *self.font_stretch {
+                FontStretch::Keyword(kw) => kw,
+                FontStretch::Stretch(percentage) => {
+                    match FontStretchKeyword::from_percentage(percentage.get()) {
+                        Some(kw) => kw,
+                        None => return Ok(()),
+                    }
+                }
+                FontStretch::System(..) => return Ok(()),
+            };
+
+            % for name in "style variant_caps weight".split():
                 if self.font_${name} != &font_${name}::get_initial_specified_value() {
                     self.font_${name}.to_css(dest)?;
                     dest.write_str(" ")?;
                 }
             % endfor
 
+            if font_stretch != FontStretchKeyword::Normal {
+                font_stretch.to_css(dest)?;
+                dest.write_str(" ")?;
+            }
+
             self.font_size.to_css(dest)?;
 
             if *self.line_height != LineHeight::normal() {
diff --git a/components/style/properties/shorthand/position.mako.rs b/components/style/properties/shorthand/position.mako.rs
index e5b07d616e4..19ca0cf1916 100644
--- a/components/style/properties/shorthand/position.mako.rs
+++ b/components/style/properties/shorthand/position.mako.rs
@@ -108,30 +108,30 @@
     }
 </%helpers:shorthand>
 
-<%helpers:shorthand name="grid-gap" sub_properties="grid-row-gap grid-column-gap"
-                    spec="https://drafts.csswg.org/css-grid/#propdef-grid-gap"
+<%helpers:shorthand name="gap" alias="grid-gap" sub_properties="row-gap column-gap"
+                    spec="https://drafts.csswg.org/css-align-3/#gap-shorthand"
                     products="gecko">
-  use properties::longhands::{grid_row_gap, grid_column_gap};
+  use properties::longhands::{row_gap, column_gap};
 
   pub fn parse_value<'i, 't>(context: &ParserContext, input: &mut Parser<'i, 't>)
                              -> Result<Longhands, ParseError<'i>> {
-      let row_gap = grid_row_gap::parse(context, input)?;
-      let column_gap = input.try(|input| grid_column_gap::parse(context, input)).unwrap_or(row_gap.clone());
+      let r_gap = row_gap::parse(context, input)?;
+      let c_gap = input.try(|input| column_gap::parse(context, input)).unwrap_or(r_gap.clone());
 
       Ok(expanded! {
-        grid_row_gap: row_gap,
-        grid_column_gap: column_gap,
+        row_gap: r_gap,
+        column_gap: c_gap,
       })
   }
 
   impl<'a> ToCss for LonghandsToSerialize<'a>  {
       fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result where W: fmt::Write {
-          if self.grid_row_gap == self.grid_column_gap {
-            self.grid_row_gap.to_css(dest)
+          if self.row_gap == self.column_gap {
+            self.row_gap.to_css(dest)
           } else {
-            self.grid_row_gap.to_css(dest)?;
+            self.row_gap.to_css(dest)?;
             dest.write_str(" ")?;
-            self.grid_column_gap.to_css(dest)
+            self.column_gap.to_css(dest)
           }
       }
   }
diff --git a/components/style/rule_tree/mod.rs b/components/style/rule_tree/mod.rs
index 25d7a8e896d..1527a743de5 100644
--- a/components/style/rule_tree/mod.rs
+++ b/components/style/rule_tree/mod.rs
@@ -162,6 +162,16 @@ const FREE_LIST_SENTINEL: *mut RuleNode = 0x01 as *mut RuleNode;
 /// another thread is currently adding an entry). We spin if we find this value.
 const FREE_LIST_LOCKED: *mut RuleNode = 0x02 as *mut RuleNode;
 
+/// A counter to track how many inner shadow roots rules deep we are.
+///
+/// This is used to handle:
+///
+/// https://drafts.csswg.org/css-scoping/#shadow-cascading
+///
+/// In particular, it'd be `0` for the innermost shadow host, `1` for the next,
+/// and so on.
+pub type ShadowCascadeOrder = u8;
+
 impl RuleTree {
     /// Construct a new rule tree.
     pub fn new() -> Self {
@@ -198,7 +208,7 @@ impl RuleTree {
         guards: &StylesheetGuards,
     ) -> StrongRuleNode
     where
-        I: Iterator<Item = (StyleSource, CascadeLevel)>,
+        I: Iterator<Item = (StyleSource, CascadeLevel, ShadowCascadeOrder)>,
     {
         use self::CascadeLevel::*;
         let mut current = self.root.clone();
@@ -206,13 +216,18 @@ impl RuleTree {
 
         let mut found_important = false;
         let mut important_style_attr = None;
-        let mut important_author = SmallVec::<[StyleSource; 4]>::new();
+
+        let mut important_same_tree = SmallVec::<[StyleSource; 4]>::new();
+        let mut important_inner_shadow = SmallVec::<[SmallVec<[StyleSource; 4]>; 4]>::new();
+        important_inner_shadow.push(SmallVec::new());
+
         let mut important_user = SmallVec::<[StyleSource; 4]>::new();
         let mut important_ua = SmallVec::<[StyleSource; 4]>::new();
         let mut transition = None;
 
-        for (source, level) in iter {
-            debug_assert!(last_level <= level, "Not really ordered");
+        let mut last_cascade_order = 0;
+        for (source, level, shadow_cascade_order) in iter {
+            debug_assert!(level >= last_level, "Not really ordered");
             debug_assert!(!level.is_important(), "Important levels handled internally");
             let any_important = {
                 let pdb = source.read(level.guard(guards));
@@ -222,7 +237,22 @@ impl RuleTree {
             if any_important {
                 found_important = true;
                 match level {
-                    AuthorNormal => important_author.push(source.clone()),
+                    InnerShadowNormal => {
+                        debug_assert!(
+                            shadow_cascade_order >= last_cascade_order,
+                            "Not really ordered"
+                        );
+                        if shadow_cascade_order > last_cascade_order &&
+                            !important_inner_shadow.last().unwrap().is_empty()
+                        {
+                            last_cascade_order = shadow_cascade_order;
+                            important_inner_shadow.push(SmallVec::new());
+                        }
+                        important_inner_shadow.last_mut().unwrap().push(source.clone())
+                    }
+                    SameTreeAuthorNormal => {
+                        important_same_tree.push(source.clone())
+                    },
                     UANormal => important_ua.push(source.clone()),
                     UserNormal => important_user.push(source.clone()),
                     StyleAttributeNormal => {
@@ -265,14 +295,20 @@ impl RuleTree {
         // followed by any transition rule.
         //
 
-        for source in important_author.drain() {
-            current = current.ensure_child(self.root.downgrade(), source, AuthorImportant);
+        for source in important_same_tree.drain() {
+            current = current.ensure_child(self.root.downgrade(), source, SameTreeAuthorImportant);
         }
 
         if let Some(source) = important_style_attr {
             current = current.ensure_child(self.root.downgrade(), source, StyleAttributeImportant);
         }
 
+        for mut list in important_inner_shadow.drain().rev() {
+            for source in list.drain() {
+                current = current.ensure_child(self.root.downgrade(), source, InnerShadowImportant);
+            }
+        }
+
         for source in important_user.drain() {
             current = current.ensure_child(self.root.downgrade(), source, UserImportant);
         }
@@ -295,9 +331,10 @@ impl RuleTree {
         applicable_declarations: &mut ApplicableDeclarationList,
         guards: &StylesheetGuards,
     ) -> StrongRuleNode {
-        let rules = applicable_declarations.drain().map(|d| d.order_and_level());
-        let rule_node = self.insert_ordered_rules_with_important(rules, guards);
-        rule_node
+        self.insert_ordered_rules_with_important(
+            applicable_declarations.drain().map(|d| d.for_rule_tree()),
+            guards,
+        )
     }
 
     /// Insert the given rules, that must be in proper order by specifity, and
@@ -381,8 +418,8 @@ impl RuleTree {
                 // also equally valid. This is less likely, and would require an
                 // in-place mutation of the source, which is, at best, fiddly,
                 // so let's skip it for now.
-                let is_here_already = match &current.get().source {
-                    &StyleSource::Declarations(ref already_here) => {
+                let is_here_already = match current.get().source {
+                    StyleSource::Declarations(ref already_here) => {
                         pdb.with_arc(|arc| Arc::ptr_eq(arc, already_here))
                     },
                     _ => unreachable!("Replacing non-declarations style?"),
@@ -500,9 +537,22 @@ const RULE_TREE_GC_INTERVAL: usize = 300;
 /// The order of variants declared here is significant, and must be in
 /// _ascending_ order of precedence.
 ///
+/// See also [4] for the Shadow DOM bits. We rely on the invariant that rules
+/// from outside the tree the element is in can't affect the element.
+///
+/// The opposite is not true (i.e., :host and ::slotted) from an "inner" shadow
+/// tree may affect an element connected to the document or an "outer" shadow
+/// tree.
+///
+/// We need to differentiate between rules from the same tree and "inner" shadow
+/// trees in order to be able to find the right position for the style attribute
+/// easily. Otherwise we wouldn't be able to avoid selector-matching when a
+/// style attribute is added or removed.
+///
 /// [1]: https://drafts.csswg.org/css-cascade/#cascade-origin
 /// [2]: https://drafts.csswg.org/css-cascade/#preshint
 /// [3]: https://html.spec.whatwg.org/multipage/#presentational-hints
+/// [4]: https://drafts.csswg.org/css-scoping/#shadow-cascading
 #[repr(u8)]
 #[derive(Clone, Copy, Debug, Eq, PartialEq, PartialOrd)]
 #[cfg_attr(feature = "servo", derive(MallocSizeOf))]
@@ -513,18 +563,27 @@ pub enum CascadeLevel {
     UserNormal,
     /// Presentational hints.
     PresHints,
-    /// Author normal rules.
-    AuthorNormal,
+    /// Shadow DOM styles from "inner" shadow trees.
+    ///
+    /// See above for why this is needed instead of merging InnerShadowNormal,
+    /// SameTreeAuthorNormal and StyleAttributeNormal inside something like
+    /// AuthorNormal.
+    InnerShadowNormal,
+    /// Author normal rules from the same tree the element is in.
+    SameTreeAuthorNormal,
     /// Style attribute normal rules.
     StyleAttributeNormal,
     /// SVG SMIL animations.
     SMILOverride,
     /// CSS animations and script-generated animations.
     Animations,
-    /// Author-supplied important rules.
-    AuthorImportant,
+    /// Author-supplied important rules from the same tree the element came
+    /// from.
+    SameTreeAuthorImportant,
     /// Style attribute important rules.
     StyleAttributeImportant,
+    /// Shadow DOM important rules.
+    InnerShadowImportant,
     /// User important rules.
     UserImportant,
     /// User-agent important rules.
@@ -571,7 +630,8 @@ impl CascadeLevel {
     #[inline]
     pub fn is_important(&self) -> bool {
         match *self {
-            CascadeLevel::AuthorImportant |
+            CascadeLevel::SameTreeAuthorImportant |
+            CascadeLevel::InnerShadowImportant |
             CascadeLevel::StyleAttributeImportant |
             CascadeLevel::UserImportant |
             CascadeLevel::UAImportant => true,
@@ -1302,11 +1362,13 @@ impl StrongRuleNode {
                     },
                     // Author rules:
                     CascadeLevel::PresHints |
-                    CascadeLevel::AuthorNormal |
+                    CascadeLevel::SameTreeAuthorNormal |
+                    CascadeLevel::InnerShadowNormal |
                     CascadeLevel::StyleAttributeNormal |
                     CascadeLevel::SMILOverride |
                     CascadeLevel::Animations |
-                    CascadeLevel::AuthorImportant |
+                    CascadeLevel::SameTreeAuthorImportant |
+                    CascadeLevel::InnerShadowImportant |
                     CascadeLevel::StyleAttributeImportant |
                     CascadeLevel::Transitions => {
                         for (id, declaration) in longhands {
diff --git a/components/style/selector_map.rs b/components/style/selector_map.rs
index 3db37a4b7f2..3b9b6f20184 100644
--- a/components/style/selector_map.rs
+++ b/components/style/selector_map.rs
@@ -14,7 +14,7 @@ use hash::{HashMap, HashSet};
 use hash::map as hash_map;
 use hashglobe::FailedAllocationError;
 use precomputed_hash::PrecomputedHash;
-use rule_tree::CascadeLevel;
+use rule_tree::{CascadeLevel, ShadowCascadeOrder};
 use selector_parser::SelectorImpl;
 use selectors::matching::{matches_selector, ElementSelectorFlags, MatchingContext};
 use selectors::parser::{Combinator, Component, SelectorIter};
@@ -163,6 +163,7 @@ impl SelectorMap<Rule> {
         context: &mut MatchingContext<E::Impl>,
         flags_setter: &mut F,
         cascade_level: CascadeLevel,
+        shadow_cascade_order: ShadowCascadeOrder,
     ) where
         E: TElement,
         F: FnMut(&E, ElementSelectorFlags),
@@ -185,6 +186,7 @@ impl SelectorMap<Rule> {
                     context,
                     flags_setter,
                     cascade_level,
+                    shadow_cascade_order,
                 )
             }
         }
@@ -198,6 +200,7 @@ impl SelectorMap<Rule> {
                     context,
                     flags_setter,
                     cascade_level,
+                    shadow_cascade_order,
                 )
             }
         });
@@ -210,6 +213,7 @@ impl SelectorMap<Rule> {
                 context,
                 flags_setter,
                 cascade_level,
+                shadow_cascade_order,
             )
         }
 
@@ -220,6 +224,7 @@ impl SelectorMap<Rule> {
             context,
             flags_setter,
             cascade_level,
+            shadow_cascade_order,
         );
 
         // Sort only the rules we just added.
@@ -235,6 +240,7 @@ impl SelectorMap<Rule> {
         context: &mut MatchingContext<E::Impl>,
         flags_setter: &mut F,
         cascade_level: CascadeLevel,
+        shadow_cascade_order: ShadowCascadeOrder,
     ) where
         E: TElement,
         F: FnMut(&E, ElementSelectorFlags),
@@ -248,7 +254,7 @@ impl SelectorMap<Rule> {
                 context,
                 flags_setter,
             ) {
-                matching_rules.push(rule.to_applicable_declaration_block(cascade_level));
+                matching_rules.push(rule.to_applicable_declaration_block(cascade_level, shadow_cascade_order));
             }
         }
     }
@@ -448,13 +454,7 @@ fn specific_bucket_for<'a>(component: &'a Component<SelectorImpl>) -> Bucket<'a>
         //
         // So inserting `span` in the rule hash makes sense since we want to
         // match the slotted <span>.
-        //
-        // FIXME(emilio, bug 1426516): The line below causes valgrind failures
-        // and it's probably a false positive, we should uncomment whenever
-        // jseward is back to confirm / whitelist it.
-        //
-        // Meanwhile taking the code path below is slower, but still correct.
-        // Component::Slotted(ref selector) => find_bucket(selector.iter()),
+        Component::Slotted(ref selector) => find_bucket(selector.iter()),
         Component::Host(Some(ref selector)) => find_bucket(selector.iter()),
         _ => Bucket::Universal,
     }
diff --git a/components/style/style_adjuster.rs b/components/style/style_adjuster.rs
index b7270976ead..4fcbffc5345 100644
--- a/components/style/style_adjuster.rs
+++ b/components/style/style_adjuster.rs
@@ -359,12 +359,10 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
     #[cfg(feature = "gecko")]
     fn adjust_for_mathvariant(&mut self) {
         use properties::longhands::_moz_math_variant::computed_value::T as MozMathVariant;
-        use properties::longhands::font_style::computed_value::T as FontStyle;
         use properties::longhands::font_weight::computed_value::T as FontWeight;
+        use values::generics::font::FontStyle;
         if self.style.get_font().clone__moz_math_variant() != MozMathVariant::None {
             let font_style = self.style.mutate_font();
-            // Sadly we don't have a nice name for the computed value
-            // of "font-weight: normal".
             font_style.set_font_weight(FontWeight::normal());
             font_style.set_font_style(FontStyle::Normal);
         }
@@ -673,17 +671,15 @@ impl<'a, 'b: 'a> StyleAdjuster<'a, 'b> {
         }
     }
 
-    /// Resolves "justify-items: auto" based on the inherited style if needed to
-    /// comply with:
+    /// Resolves "justify-items: legacy" based on the inherited style if needed
+    /// to comply with:
     ///
     /// <https://drafts.csswg.org/css-align/#valdef-justify-items-legacy>
-    ///
-    /// (Note that "auto" is being renamed to "legacy")
     #[cfg(feature = "gecko")]
     fn adjust_for_justify_items(&mut self) {
         use values::specified::align;
         let justify_items = self.style.get_position().clone_justify_items();
-        if justify_items.specified.0 != align::AlignFlags::AUTO {
+        if justify_items.specified.0 != align::AlignFlags::LEGACY {
             return;
         }
 
diff --git a/components/style/stylesheets/import_rule.rs b/components/style/stylesheets/import_rule.rs
index fb50ec69732..576cb31eff3 100644
--- a/components/style/stylesheets/import_rule.rs
+++ b/components/style/stylesheets/import_rule.rs
@@ -171,10 +171,9 @@ pub struct ImportRule {
     /// The `<url>` this `@import` rule is loading.
     pub url: CssUrl,
 
-    /// The stylesheet is always present.
-    ///
-    /// It contains an empty list of rules and namespace set that is updated
-    /// when it loads.
+    /// The stylesheet is always present. However, in the case of gecko async
+    /// parsing, we don't actually have a Gecko sheet at first, and so the
+    /// ImportSheet just has stub behavior until it appears.
     pub stylesheet: ImportSheet,
 
     /// The line and column of the rule's source code.
diff --git a/components/style/stylist.rs b/components/style/stylist.rs
index 931b667d38b..ccd668b0bed 100644
--- a/components/style/stylist.rs
+++ b/components/style/stylist.rs
@@ -23,7 +23,7 @@ use media_queries::Device;
 use properties::{self, CascadeFlags, ComputedValues};
 use properties::{AnimationRules, PropertyDeclarationBlock};
 use rule_cache::{RuleCache, RuleCacheConditions};
-use rule_tree::{CascadeLevel, RuleTree, StrongRuleNode, StyleSource};
+use rule_tree::{CascadeLevel, RuleTree, ShadowCascadeOrder, StrongRuleNode, StyleSource};
 use selector_map::{PrecomputedHashMap, SelectorMap, SelectorMapEntry};
 use selector_parser::{PerPseudoElementMap, PseudoElement, SelectorImpl, SnapshotMap};
 use selectors::NthIndexCache;
@@ -693,7 +693,7 @@ impl Stylist {
 
         match declarations {
             Some(decls) => self.rule_tree.insert_ordered_rules_with_important(
-                decls.into_iter().map(|a| (a.source.clone(), a.level())),
+                decls.into_iter().map(|a| a.clone().for_rule_tree()),
                 guards,
             ),
             None => self.rule_tree.root().clone(),
@@ -1020,7 +1020,7 @@ impl Stylist {
             );
             if !declarations.is_empty() {
                 let rule_node = self.rule_tree.insert_ordered_rules_with_important(
-                    declarations.drain().map(|a| a.order_and_level()),
+                    declarations.drain().map(|a| a.for_rule_tree()),
                     guards,
                 );
                 if rule_node != *self.rule_tree.root() {
@@ -1187,6 +1187,7 @@ impl Stylist {
                 context,
                 flags_setter,
                 CascadeLevel::UANormal,
+                0,
             );
         }
 
@@ -1208,6 +1209,7 @@ impl Stylist {
                     context,
                     flags_setter,
                     CascadeLevel::UserNormal,
+                    0,
                 );
             }
         }
@@ -1232,6 +1234,7 @@ impl Stylist {
         }
 
         let mut match_document_author_rules = matches_author_rules;
+        let mut shadow_cascade_order = 0;
 
         // XBL / Shadow DOM rules, which are author rules too.
         //
@@ -1249,9 +1252,11 @@ impl Stylist {
                             applicable_declarations,
                             context,
                             flags_setter,
-                            CascadeLevel::AuthorNormal,
+                            CascadeLevel::InnerShadowNormal,
+                            shadow_cascade_order,
                         );
                     });
+                    shadow_cascade_order += 1;
                 }
             }
 
@@ -1275,9 +1280,11 @@ impl Stylist {
                             applicable_declarations,
                             context,
                             flags_setter,
-                            CascadeLevel::AuthorNormal,
+                            CascadeLevel::InnerShadowNormal,
+                            shadow_cascade_order,
                         );
                     });
+                    shadow_cascade_order += 1;
                 }
             }
 
@@ -1291,9 +1298,11 @@ impl Stylist {
                             applicable_declarations,
                             context,
                             flags_setter,
-                            CascadeLevel::AuthorNormal,
+                            CascadeLevel::SameTreeAuthorNormal,
+                            shadow_cascade_order,
                         );
                     });
+                    shadow_cascade_order += 1;
                 }
 
                 match_document_author_rules = false;
@@ -1309,10 +1318,6 @@ impl Stylist {
                 if let Some(map) = cascade_data.normal_rules(pseudo_element) {
                     // NOTE(emilio): This is needed because the XBL stylist may
                     // think it has a different quirks mode than the document.
-                    //
-                    // FIXME(emilio): this should use the same VisitedMatchingMode
-                    // as `context`, write a test-case of :visited not working on
-                    // Shadow DOM and fix it!
                     let mut matching_context = MatchingContext::new(
                         context.matching_mode(),
                         context.bloom_filter,
@@ -1322,13 +1327,16 @@ impl Stylist {
                     matching_context.pseudo_element_matching_fn =
                         context.pseudo_element_matching_fn;
 
+                    // SameTreeAuthorNormal instead of InnerShadowNormal to
+                    // preserve behavior, though that's kinda fishy...
                     map.get_all_matching_rules(
                         element,
                         rule_hash_target,
                         applicable_declarations,
                         &mut matching_context,
                         flags_setter,
-                        CascadeLevel::AuthorNormal,
+                        CascadeLevel::SameTreeAuthorNormal,
+                        shadow_cascade_order,
                     );
                 }
             });
@@ -1344,7 +1352,8 @@ impl Stylist {
                     applicable_declarations,
                     context,
                     flags_setter,
-                    CascadeLevel::AuthorNormal,
+                    CascadeLevel::SameTreeAuthorNormal,
+                    shadow_cascade_order,
                 );
             }
         }
@@ -2172,6 +2181,7 @@ impl CascadeData {
                                         self.rules_source_order,
                                         CascadeLevel::UANormal,
                                         selector.specificity(),
+                                        0,
                                     ));
                                 continue;
                             }
@@ -2468,9 +2478,10 @@ impl Rule {
     pub fn to_applicable_declaration_block(
         &self,
         level: CascadeLevel,
+        shadow_cascade_order: ShadowCascadeOrder,
     ) -> ApplicableDeclarationBlock {
         let source = StyleSource::Style(self.style_rule.clone());
-        ApplicableDeclarationBlock::new(source, self.source_order, level, self.specificity())
+        ApplicableDeclarationBlock::new(source, self.source_order, level, self.specificity(), shadow_cascade_order)
     }
 
     /// Creates a new Rule.
diff --git a/components/style/values/computed/align.rs b/components/style/values/computed/align.rs
index 940e3f747b8..1a26e41fd24 100644
--- a/components/style/values/computed/align.rs
+++ b/components/style/values/computed/align.rs
@@ -20,10 +20,10 @@ pub use super::specified::{AlignSelf, JustifySelf};
 /// In particular, `justify-items` is a reset property, so we ought to be able
 /// to share its computed representation across elements as long as they match
 /// the same rules. Except that it's not true if the specified value for
-/// `justify-items` is `auto` and the computed value of the parent has the
+/// `justify-items` is `legacy` and the computed value of the parent has the
 /// `legacy` modifier.
 ///
-/// So instead of computing `auto` "normally" looking at get_parent_position(),
+/// So instead of computing `legacy` "normally" looking at get_parent_position(),
 /// marking it as uncacheable, we carry the specified value around and handle
 /// the special case in `StyleAdjuster` instead, only when the result of the
 /// computation would vary.
@@ -35,18 +35,21 @@ pub use super::specified::{AlignSelf, JustifySelf};
 /// See the discussion in https://bugzil.la/1384542.
 #[derive(Clone, Copy, Debug, Eq, PartialEq, ToCss)]
 pub struct JustifyItems {
-    /// The specified value for the property. Can contain `auto`.
+    /// The specified value for the property. Can contain the bare `legacy`
+    /// keyword.
     #[css(skip)]
     pub specified: specified::JustifyItems,
-    /// The computed value for the property. Cannot contain `auto`.
+    /// The computed value for the property. Cannot contain the bare `legacy`
+    /// keyword, but note that it could contain it in combination with other
+    /// keywords like `left`, `right` or `center`.
     pub computed: specified::JustifyItems,
 }
 
 impl JustifyItems {
-    /// Returns the `auto` value.
-    pub fn auto() -> Self {
+    /// Returns the `legacy` value.
+    pub fn legacy() -> Self {
         Self {
-            specified: specified::JustifyItems::auto(),
+            specified: specified::JustifyItems::legacy(),
             computed: specified::JustifyItems::normal(),
         }
     }
@@ -59,13 +62,13 @@ impl ToComputedValue for specified::JustifyItems {
     fn to_computed_value(&self, _context: &Context) -> JustifyItems {
         use values::specified::align;
         let specified = *self;
-        let computed = if self.0 != align::AlignFlags::AUTO {
+        let computed = if self.0 != align::AlignFlags::LEGACY {
             *self
         } else {
             // If the inherited value of `justify-items` includes the
-            // `legacy` keyword, `auto` computes to the inherited value,
-            // but we assume it computes to `normal`, and handle that
-            // special-case in StyleAdjuster.
+            // `legacy` keyword, `legacy` computes to the inherited value, but
+            // we assume it computes to `normal`, and handle that special-case
+            // in StyleAdjuster.
             Self::normal()
         };
 
diff --git a/components/style/values/computed/angle.rs b/components/style/values/computed/angle.rs
index ec269df9796..67ea5d1231b 100644
--- a/components/style/values/computed/angle.rs
+++ b/components/style/values/computed/angle.rs
@@ -64,6 +64,12 @@ impl Angle {
         radians.min(f64::MAX).max(f64::MIN)
     }
 
+    /// Return the value in degrees.
+    pub fn degrees(&self) -> f32 {
+        use std::f32::consts::PI;
+        self.radians() * 360. / (2. * PI)
+    }
+
     /// <https://drafts.csswg.org/css-transitions/#animtype-number>
     #[inline]
     fn animate_fallback(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
diff --git a/components/style/values/computed/font.rs b/components/style/values/computed/font.rs
index c270969a52f..1ca8400c16a 100644
--- a/components/style/values/computed/font.rs
+++ b/components/style/values/computed/font.rs
@@ -22,23 +22,38 @@ use std::slice;
 use style_traits::{CssWriter, ParseError, ToCss};
 use values::CSSFloat;
 use values::animated::{ToAnimatedValue, ToAnimatedZero};
-use values::computed::{Context, Integer, NonNegativeLength, Number, ToComputedValue};
-use values::generics::font::{FeatureTagValue, FontSettings};
-use values::generics::font::{KeywordInfo as GenericKeywordInfo, VariationValue};
-use values::specified::font as specified;
+use values::computed::{Angle, Context, Integer, NonNegativeLength, Number, ToComputedValue};
+use values::generics::font::{self as generics, FeatureTagValue, FontSettings, VariationValue};
+use values::specified::font::{self as specified, MIN_FONT_WEIGHT, MAX_FONT_WEIGHT};
 use values::specified::length::{FontBaseSize, NoCalcLength};
 
 pub use values::computed::Length as MozScriptMinSize;
 pub use values::specified::font::{FontSynthesis, MozScriptSizeMultiplier, XLang, XTextZoom};
+pub use values::computed::NonNegativePercentage as FontStretch;
 
-/// As of CSS Fonts Module Level 3, only the following values are
-/// valid: 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
+/// A value for the font-weight property per:
 ///
-/// However, system fonts may provide other values. Pango
-/// may provide 350, 380, and 1000 (on top of the existing values), for example.
-#[derive(Clone, ComputeSquaredDistance, Copy, Debug, Eq, Hash, MallocSizeOf, PartialEq, ToCss)]
+/// https://drafts.csswg.org/css-fonts-4/#propdef-font-weight
+///
+/// This is effectively just a `Number`.
+#[derive(Clone, ComputeSquaredDistance, Copy, Debug, MallocSizeOf, PartialEq,
+         ToCss)]
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
-pub struct FontWeight(pub u16);
+pub struct FontWeight(pub Number);
+
+impl ToAnimatedValue for FontWeight {
+    type AnimatedValue = Number;
+
+    #[inline]
+    fn to_animated_value(self) -> Self::AnimatedValue {
+        self.0
+    }
+
+    #[inline]
+    fn from_animated_value(animated: Self::AnimatedValue) -> Self {
+        FontWeight(animated.max(MIN_FONT_WEIGHT).min(MAX_FONT_WEIGHT))
+    }
+}
 
 #[derive(Animate, Clone, ComputeSquaredDistance, Copy, Debug, MallocSizeOf, PartialEq,
          ToAnimatedZero, ToCss)]
@@ -52,26 +67,17 @@ pub struct FontSize {
 }
 
 /// Additional information for computed keyword-derived font sizes.
-pub type KeywordInfo = GenericKeywordInfo<NonNegativeLength>;
+pub type KeywordInfo = generics::KeywordInfo<NonNegativeLength>;
 
 impl FontWeight {
     /// Value for normal
     pub fn normal() -> Self {
-        FontWeight(400)
+        FontWeight(400.)
     }
 
     /// Value for bold
     pub fn bold() -> Self {
-        FontWeight(700)
-    }
-
-    /// Convert from an integer to Weight
-    pub fn from_int(n: i32) -> Result<Self, ()> {
-        if n >= 100 && n <= 900 && n % 100 == 0 {
-            Ok(FontWeight(n as u16))
-        } else {
-            Err(())
-        }
+        FontWeight(700.)
     }
 
     /// Convert from an Gecko weight
@@ -80,33 +86,39 @@ impl FontWeight {
         // we allow a wider range of weights than is parseable
         // because system fonts may provide custom values
         let weight = unsafe { bindings::Gecko_FontWeight_ToFloat(weight) };
-        FontWeight(weight as u16)
+        FontWeight(weight)
     }
 
     /// Weither this weight is bold
     pub fn is_bold(&self) -> bool {
-        self.0 > 500
+        self.0 > 500.
     }
 
-    /// Return the bolder weight
+    /// Return the bolder weight.
+    ///
+    /// See the table in:
+    /// https://drafts.csswg.org/css-fonts-4/#font-weight-numeric-values
     pub fn bolder(self) -> Self {
-        if self.0 < 400 {
-            FontWeight(400)
-        } else if self.0 < 600 {
-            FontWeight(700)
+        if self.0 < 350. {
+            FontWeight(400.)
+        } else if self.0 < 550. {
+            FontWeight(700.)
         } else {
-            FontWeight(900)
+            FontWeight(self.0.max(900.))
         }
     }
 
-    /// Returns the lighter weight
+    /// Return the lighter weight.
+    ///
+    /// See the table in:
+    /// https://drafts.csswg.org/css-fonts-4/#font-weight-numeric-values
     pub fn lighter(self) -> Self {
-        if self.0 < 600 {
-            FontWeight(100)
-        } else if self.0 < 800 {
-            FontWeight(400)
+        if self.0 < 550. {
+            FontWeight(self.0.min(100.))
+        } else if self.0 < 750. {
+            FontWeight(400.)
         } else {
-            FontWeight(700)
+            FontWeight(700.)
         }
     }
 }
@@ -816,3 +828,91 @@ impl ToComputedValue for specified::MozScriptLevel {
         specified::MozScriptLevel::MozAbsolute(*other as i32)
     }
 }
+
+/// A wrapper over an `Angle`, that handles clamping to the appropriate range
+/// for `font-style` animation.
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss)]
+#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
+pub struct FontStyleAngle(pub Angle);
+
+impl ToAnimatedValue for FontStyleAngle {
+    type AnimatedValue = Angle;
+
+    #[inline]
+    fn to_animated_value(self) -> Self::AnimatedValue {
+        self.0
+    }
+
+    #[inline]
+    fn from_animated_value(animated: Self::AnimatedValue) -> Self {
+        FontStyleAngle(Angle::Deg(
+            animated.degrees()
+                .min(specified::FONT_STYLE_OBLIQUE_MAX_ANGLE_DEGREES)
+                .max(specified::FONT_STYLE_OBLIQUE_MIN_ANGLE_DEGREES)
+        ))
+    }
+}
+
+/// The computed value of `font-style`.
+///
+/// FIXME(emilio): Angle should be a custom type to handle clamping during
+/// animation.
+pub type FontStyle = generics::FontStyle<FontStyleAngle>;
+
+impl FontStyle {
+    /// The `normal` value.
+    #[inline]
+    pub fn normal() -> Self {
+        generics::FontStyle::Normal
+    }
+
+    /// The default angle for font-style: oblique. This is 20deg per spec:
+    ///
+    /// https://drafts.csswg.org/css-fonts-4/#valdef-font-style-oblique-angle
+    #[inline]
+    pub fn default_angle() -> FontStyleAngle {
+        FontStyleAngle(Angle::Deg(specified::DEFAULT_FONT_STYLE_OBLIQUE_ANGLE_DEGREES))
+    }
+
+
+    /// Get the font style from Gecko's nsFont struct.
+    #[cfg(feature = "gecko")]
+    pub fn from_gecko(style: structs::FontSlantStyle) -> Self {
+        let mut angle = 0.;
+        let mut italic = false;
+        let mut normal = false;
+        unsafe {
+            bindings::Gecko_FontSlantStyle_Get(style, &mut normal, &mut italic, &mut angle);
+        }
+        if normal {
+            return generics::FontStyle::Normal;
+        }
+        if italic {
+            return generics::FontStyle::Italic;
+        }
+        generics::FontStyle::Oblique(FontStyleAngle(Angle::Deg(angle)))
+    }
+}
+
+impl ToCss for FontStyle {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: fmt::Write,
+    {
+        match *self {
+            generics::FontStyle::Normal => dest.write_str("normal"),
+            generics::FontStyle::Italic => dest.write_str("italic"),
+            generics::FontStyle::Oblique(ref angle) => {
+                dest.write_str("oblique")?;
+                // Use `degrees` instead of just comparing Angle because
+                // `degrees` can return slightly different values due to
+                // floating point conversions.
+                if angle.0.degrees() != Self::default_angle().0.degrees() {
+                    dest.write_char(' ')?;
+                    angle.to_css(dest)?;
+                }
+                Ok(())
+            }
+        }
+    }
+}
diff --git a/components/style/values/computed/mod.rs b/components/style/values/computed/mod.rs
index 67529efb06f..4adf33253e8 100644
--- a/components/style/values/computed/mod.rs
+++ b/components/style/values/computed/mod.rs
@@ -39,8 +39,8 @@ pub use self::angle::Angle;
 pub use self::background::{BackgroundRepeat, BackgroundSize};
 pub use self::border::{BorderImageRepeat, BorderImageSideWidth, BorderImageSlice, BorderImageWidth};
 pub use self::border::{BorderCornerRadius, BorderRadius, BorderSpacing};
-pub use self::font::{FontSize, FontSizeAdjust, FontSynthesis, FontVariantAlternates, FontWeight};
-pub use self::font::{FontFamily, FontLanguageOverride, FontVariantEastAsian, FontVariationSettings};
+pub use self::font::{FontSize, FontSizeAdjust, FontStretch, FontSynthesis, FontVariantAlternates, FontWeight};
+pub use self::font::{FontFamily, FontLanguageOverride, FontStyle, FontVariantEastAsian, FontVariationSettings};
 pub use self::font::{FontFeatureSettings, FontVariantLigatures, FontVariantNumeric};
 pub use self::font::{MozScriptLevel, MozScriptMinSize, MozScriptSizeMultiplier, XLang, XTextZoom};
 pub use self::box_::{AnimationIterationCount, AnimationName, Contain, Display};
@@ -66,7 +66,7 @@ pub use self::list::Quotes;
 #[cfg(feature = "gecko")]
 pub use self::list::ListStyleType;
 pub use self::outline::OutlineStyle;
-pub use self::percentage::Percentage;
+pub use self::percentage::{Percentage, NonNegativePercentage};
 pub use self::pointing::{CaretColor, Cursor};
 #[cfg(feature = "gecko")]
 pub use self::pointing::CursorImage;
diff --git a/components/style/values/computed/percentage.rs b/components/style/values/computed/percentage.rs
index ee881a22019..7ca504d2aff 100644
--- a/components/style/values/computed/percentage.rs
+++ b/components/style/values/computed/percentage.rs
@@ -7,6 +7,8 @@
 use std::fmt;
 use style_traits::{CssWriter, ToCss};
 use values::{serialize_percentage, CSSFloat};
+use values::animated::ToAnimatedValue;
+use values::generics::NonNegative;
 
 /// A computed percentage.
 #[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
@@ -48,3 +50,34 @@ impl ToCss for Percentage {
         serialize_percentage(self.0, dest)
     }
 }
+
+/// A wrapper over a `Percentage`, whose value should be clamped to 0.
+pub type NonNegativePercentage = NonNegative<Percentage>;
+
+impl NonNegativePercentage {
+    /// 0%
+    #[inline]
+    pub fn zero() -> Self {
+        NonNegative(Percentage::zero())
+    }
+
+    /// 100%
+    #[inline]
+    pub fn hundred() -> Self {
+        NonNegative(Percentage::hundred())
+    }
+}
+
+impl ToAnimatedValue for NonNegativePercentage {
+    type AnimatedValue = Percentage;
+
+    #[inline]
+    fn to_animated_value(self) -> Self::AnimatedValue {
+        self.0
+    }
+
+    #[inline]
+    fn from_animated_value(animated: Self::AnimatedValue) -> Self {
+        NonNegative(animated.clamp_to_non_negative())
+    }
+}
diff --git a/components/style/values/generics/font.rs b/components/style/values/generics/font.rs
index d951756f43b..cbcd64502c4 100644
--- a/components/style/values/generics/font.rs
+++ b/components/style/values/generics/font.rs
@@ -231,3 +231,18 @@ impl ToCss for KeywordSize {
         })
     }
 }
+
+/// A generic value for the `font-style` property.
+///
+/// https://drafts.csswg.org/css-fonts-4/#font-style-prop
+#[allow(missing_docs)]
+#[derive(Animate, Clone, ComputeSquaredDistance, Copy, Debug, MallocSizeOf,
+         PartialEq, ToAnimatedValue, ToAnimatedZero)]
+#[cfg_attr(feature = "servo", derive(Deserialize, Serialize))]
+pub enum FontStyle<Angle> {
+    #[animation(error)]
+    Normal,
+    #[animation(error)]
+    Italic,
+    Oblique(Angle),
+}
diff --git a/components/style/values/specified/align.rs b/components/style/values/specified/align.rs
index 918c4ddf8ed..7b9b003a50c 100644
--- a/components/style/values/specified/align.rs
+++ b/components/style/values/specified/align.rs
@@ -9,9 +9,8 @@
 use cssparser::Parser;
 use gecko_bindings::structs;
 use parser::{Parse, ParserContext};
-use selectors::parser::SelectorParseErrorKind;
 use std::fmt::{self, Write};
-use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
+use style_traits::{CssWriter, ParseError, ToCss};
 
 bitflags! {
     /// Constants shared by multiple CSS Box Alignment properties
@@ -81,14 +80,26 @@ impl ToCss for AlignFlags {
     where
         W: Write,
     {
-        match *self & AlignFlags::FLAG_BITS {
-            AlignFlags::LEGACY => dest.write_str("legacy ")?,
+        let extra_flags = *self & AlignFlags::FLAG_BITS;
+        let value = self.value();
+
+        match extra_flags {
+            AlignFlags::LEGACY => {
+                dest.write_str("legacy")?;
+                if value.is_empty() {
+                    return Ok(());
+                }
+                dest.write_char(' ')?;
+            },
             AlignFlags::SAFE => dest.write_str("safe ")?,
             // Don't serialize "unsafe", since it's the default.
-            _ => {},
+            AlignFlags::UNSAFE => {},
+            _ => {
+                debug_assert_eq!(extra_flags, AlignFlags::empty());
+            },
         }
 
-        dest.write_str(match self.value() {
+        dest.write_str(match value {
             AlignFlags::AUTO => "auto",
             AlignFlags::NORMAL => "normal",
             AlignFlags::START => "start",
@@ -436,10 +447,10 @@ impl Parse for AlignItems {
 pub struct JustifyItems(pub AlignFlags);
 
 impl JustifyItems {
-    /// The initial value 'auto'
+    /// The initial value 'legacy'
     #[inline]
-    pub fn auto() -> Self {
-        JustifyItems(AlignFlags::AUTO)
+    pub fn legacy() -> Self {
+        JustifyItems(AlignFlags::LEGACY)
     }
 
     /// The value 'normal'
@@ -462,24 +473,12 @@ impl Parse for JustifyItems {
             return Ok(JustifyItems(baseline));
         }
 
-        // auto | normal | stretch
-        //
-        // FIXME(emilio): auto is no longer a keyword in the current spec, and
-        // has been renamed to legacy, but that needs different changes because
-        // right now it's the initial value for both style systems, and has that
-        // weird behavior of "inheriting" into descendants.
-        //
-        // Fix this in both.
-        //
-        // See also:
-        //   https://bugs.webkit.org/show_bug.cgi?id=172711
-        //   https://bugs.chromium.org/p/chromium/issues/detail?id=726148
-        //
-        if let Ok(value) = input.try(parse_auto_normal_stretch) {
+        // normal | stretch
+        if let Ok(value) = input.try(parse_normal_stretch) {
             return Ok(JustifyItems(value));
         }
 
-        // [ legacy || [ left | right | center ] ]
+        // legacy | [ legacy && [ left | right | center ] ]
         if let Ok(value) = input.try(parse_legacy) {
             return Ok(JustifyItems(value));
         }
@@ -567,29 +566,30 @@ fn parse_self_position<'i, 't>(
     })
 }
 
-// [ legacy && [ left | right | center ] ]
-fn parse_legacy<'i, 't>(input: &mut Parser<'i, 't>) -> Result<AlignFlags, ParseError<'i>> {
-    let a_location = input.current_source_location();
-    let a = input.expect_ident()?.clone();
-    let b_location = input.current_source_location();
-    let b = input.expect_ident()?;
-    if a.eq_ignore_ascii_case("legacy") {
-        (match_ignore_ascii_case! { &b,
-            "left" => Ok(AlignFlags::LEGACY | AlignFlags::LEFT),
-            "right" => Ok(AlignFlags::LEGACY | AlignFlags::RIGHT),
-            "center" => Ok(AlignFlags::LEGACY | AlignFlags::CENTER),
-            _ => Err(())
-        }).map_err(|()| {
-            b_location.new_custom_error(SelectorParseErrorKind::UnexpectedIdent(b.clone()))
-        })
-    } else if b.eq_ignore_ascii_case("legacy") {
-        (match_ignore_ascii_case! { &a,
-            "left" => Ok(AlignFlags::LEGACY | AlignFlags::LEFT),
-            "right" => Ok(AlignFlags::LEGACY | AlignFlags::RIGHT),
-            "center" => Ok(AlignFlags::LEGACY | AlignFlags::CENTER),
-            _ => Err(())
-        }).map_err(|()| a_location.new_custom_error(SelectorParseErrorKind::UnexpectedIdent(a)))
-    } else {
-        Err(a_location.new_custom_error(StyleParseErrorKind::UnspecifiedError))
-    }
+fn parse_left_right_center<'i, 't>(
+    input: &mut Parser<'i, 't>,
+) -> Result<AlignFlags, ParseError<'i>> {
+    Ok(try_match_ident_ignore_ascii_case! { input,
+        "left" => AlignFlags::LEFT,
+        "right" => AlignFlags::RIGHT,
+        "center" => AlignFlags::CENTER,
+    })
+}
+
+// legacy | [ legacy && [ left | right | center ] ]
+fn parse_legacy<'i, 't>(input: &mut Parser<'i, 't>) -> Result<AlignFlags, ParseError<'i>> {
+    let flags = try_match_ident_ignore_ascii_case! { input,
+        "legacy" => {
+            let flags = input.try(parse_left_right_center)
+                .unwrap_or(AlignFlags::empty());
+
+            return Ok(AlignFlags::LEGACY | flags)
+        }
+        "left" => AlignFlags::LEFT,
+        "right" => AlignFlags::RIGHT,
+        "center" => AlignFlags::CENTER,
+    };
+
+    input.expect_ident_matching("legacy")?;
+    Ok(AlignFlags::LEGACY | flags)
 }
diff --git a/components/style/values/specified/angle.rs b/components/style/values/specified/angle.rs
index 90b990bf8ce..3f49862e406 100644
--- a/components/style/values/specified/angle.rs
+++ b/components/style/values/specified/angle.rs
@@ -41,13 +41,19 @@ impl ToCss for Angle {
     }
 }
 
+// FIXME(emilio): Probably computed angles shouldn't preserve the unit and
+// should serialize to degrees per:
+//
+// https://drafts.csswg.org/css-values/#compat
 impl ToComputedValue for Angle {
     type ComputedValue = ComputedAngle;
 
+    #[inline]
     fn to_computed_value(&self, _context: &Context) -> Self::ComputedValue {
         self.value
     }
 
+    #[inline]
     fn from_computed_value(computed: &Self::ComputedValue) -> Self {
         Angle {
             value: *computed,
@@ -89,6 +95,12 @@ impl Angle {
         }
     }
 
+    /// Whether this specified angle came from a `calc()` expression.
+    #[inline]
+    pub fn was_calc(&self) -> bool {
+        self.was_calc
+    }
+
     /// Returns the amount of radians this angle represents.
     #[inline]
     pub fn radians(self) -> f32 {
@@ -98,8 +110,7 @@ impl Angle {
     /// Returns the amount of degrees this angle represents.
     #[inline]
     pub fn degrees(self) -> f32 {
-        use std::f32::consts::PI;
-        self.radians() * 360. / (2. * PI)
+        self.value.degrees()
     }
 
     /// Returns `0deg`.
diff --git a/components/style/values/specified/font.rs b/components/style/values/specified/font.rs
index a386a329ac8..fa4d972ef16 100644
--- a/components/style/values/specified/font.rs
+++ b/components/style/values/specified/font.rs
@@ -17,79 +17,108 @@ use properties::longhands::system_font::SystemFont;
 use std::fmt::{self, Write};
 use style_traits::{CssWriter, ParseError, StyleParseErrorKind, ToCss};
 use values::CustomIdent;
+use values::computed::{Angle as ComputedAngle, Percentage as ComputedPercentage};
 use values::computed::{font as computed, Context, Length, NonNegativeLength, ToComputedValue};
-use values::computed::font::{FamilyName, FontFamilyList, SingleFontFamily};
-use values::generics::font::{FeatureTagValue, FontSettings, FontTag};
-use values::generics::font::{KeywordInfo as GenericKeywordInfo, KeywordSize, VariationValue};
-use values::specified::{AllowQuirks, Integer, LengthOrPercentage, NoCalcLength, Number};
+use values::computed::font::{FamilyName, FontFamilyList, FontStyleAngle, SingleFontFamily};
+use values::generics::NonNegative;
+use values::generics::font::{KeywordSize, VariationValue};
+use values::generics::font::{self as generics, FeatureTagValue, FontSettings, FontTag};
+use values::specified::{AllowQuirks, Angle, Integer, LengthOrPercentage, NoCalcLength, Number, Percentage};
 use values::specified::length::{FontBaseSize, AU_PER_PT, AU_PER_PX};
 
+// FIXME(emilio): The system font code is copy-pasta, and should be cleaned up.
+macro_rules! system_font_methods {
+    ($ty:ident, $field:ident) => {
+        system_font_methods!($ty);
+
+        fn compute_system(&self, _context: &Context) -> <$ty as ToComputedValue>::ComputedValue {
+            debug_assert!(matches!(*self, $ty::System(..)));
+            #[cfg(feature = "gecko")]
+            {
+                _context.cached_system_font.as_ref().unwrap().$field.clone()
+            }
+            #[cfg(feature = "servo")]
+            {
+                unreachable!()
+            }
+        }
+    };
+
+    ($ty:ident) => {
+        /// Get a specified value that represents a system font.
+        pub fn system_font(f: SystemFont) -> Self {
+            $ty::System(f)
+        }
+
+        /// Retreive a SystemFont from the specified value.
+        pub fn get_system(&self) -> Option<SystemFont> {
+            if let $ty::System(s) = *self {
+                Some(s)
+            } else {
+                None
+            }
+        }
+    }
+}
+
 const DEFAULT_SCRIPT_MIN_SIZE_PT: u32 = 8;
 const DEFAULT_SCRIPT_SIZE_MULTIPLIER: f64 = 0.71;
 
-#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, PartialEq, ToCss)]
-/// A specified font-weight value
+/// The minimum font-weight value per:
+///
+/// https://drafts.csswg.org/css-fonts-4/#font-weight-numeric-values
+pub const MIN_FONT_WEIGHT: f32 = 1.;
+
+/// The maximum font-weight value per:
+///
+/// https://drafts.csswg.org/css-fonts-4/#font-weight-numeric-values
+pub const MAX_FONT_WEIGHT: f32 = 1000.;
+
+/// A specified font-weight value.
+///
+/// https://drafts.csswg.org/css-fonts-4/#propdef-font-weight
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss)]
 pub enum FontWeight {
-    /// Normal variant
-    Normal,
-    /// Bold variant
-    Bold,
+    /// `<font-weight-absolute>`
+    Absolute(AbsoluteFontWeight),
     /// Bolder variant
     Bolder,
     /// Lighter variant
     Lighter,
-    /// Computed weight variant
-    Weight(computed::FontWeight),
-    /// System font varaint
+    /// System font variant.
     System(SystemFont),
 }
 
 impl FontWeight {
+    system_font_methods!(FontWeight, font_weight);
+
+    /// `normal`
+    #[inline]
+    pub fn normal() -> Self {
+        FontWeight::Absolute(AbsoluteFontWeight::Normal)
+    }
+
     /// Get a specified FontWeight from a gecko keyword
     pub fn from_gecko_keyword(kw: u32) -> Self {
-        computed::FontWeight::from_int(kw as i32)
-            .map(FontWeight::Weight)
-            .expect("Found unexpected value in style struct for font-weight property")
-    }
-
-    /// Get a specified FontWeight from a SystemFont
-    pub fn system_font(f: SystemFont) -> Self {
-        FontWeight::System(f)
-    }
-
-    /// Retreive a SystemFont from FontWeight
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontWeight::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
+        debug_assert!(kw % 100 == 0);
+        debug_assert!(kw as f32 <= MAX_FONT_WEIGHT);
+        FontWeight::Absolute(AbsoluteFontWeight::Weight(Number::new(kw as f32)))
     }
 }
 
 impl Parse for FontWeight {
     fn parse<'i, 't>(
-        _: &ParserContext,
+        context: &ParserContext,
         input: &mut Parser<'i, 't>,
     ) -> Result<FontWeight, ParseError<'i>> {
-        let result = match *input.next()? {
-            Token::Ident(ref ident) => {
-                match_ignore_ascii_case! { ident,
-                    "normal" => Ok(FontWeight::Normal),
-                    "bold" => Ok(FontWeight::Bold),
-                    "bolder" => Ok(FontWeight::Bolder),
-                    "lighter" => Ok(FontWeight::Lighter),
-                    _ => Err(()),
-                }
-            },
-            Token::Number {
-                int_value: Some(value),
-                ..
-            } => computed::FontWeight::from_int(value).map(FontWeight::Weight),
-            _ => Err(()),
-        };
+        if let Ok(absolute) = input.try(|input| AbsoluteFontWeight::parse(context, input)) {
+            return Ok(FontWeight::Absolute(absolute));
+        }
 
-        result.map_err(|_| input.new_custom_error(StyleParseErrorKind::UnspecifiedError))
+        Ok(try_match_ident_ignore_ascii_case! { input,
+            "bolder" => FontWeight::Bolder,
+            "lighter" => FontWeight::Lighter,
+        })
     }
 }
 
@@ -99,9 +128,7 @@ impl ToComputedValue for FontWeight {
     #[inline]
     fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
         match *self {
-            FontWeight::Weight(weight) => weight,
-            FontWeight::Normal => computed::FontWeight::normal(),
-            FontWeight::Bold => computed::FontWeight::bold(),
+            FontWeight::Absolute(ref abs) => abs.compute(),
             FontWeight::Bolder => context
                 .builder
                 .get_parent_font()
@@ -112,21 +139,365 @@ impl ToComputedValue for FontWeight {
                 .get_parent_font()
                 .clone_font_weight()
                 .lighter(),
-            #[cfg(feature = "gecko")]
-            FontWeight::System(_) => context
-                .cached_system_font
-                .as_ref()
-                .unwrap()
-                .font_weight
-                .clone(),
-            #[cfg(not(feature = "gecko"))]
-            FontWeight::System(_) => unreachable!(),
+            FontWeight::System(_) => self.compute_system(context),
         }
     }
 
     #[inline]
     fn from_computed_value(computed: &computed::FontWeight) -> Self {
-        FontWeight::Weight(*computed)
+        FontWeight::Absolute(AbsoluteFontWeight::Weight(
+            Number::from_computed_value(&computed.0)
+        ))
+    }
+}
+
+/// An absolute font-weight value for a @font-face rule.
+///
+/// https://drafts.csswg.org/css-fonts-4/#font-weight-absolute-values
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss)]
+pub enum AbsoluteFontWeight {
+    /// A `<number>`, with the additional constraints specified in:
+    ///
+    ///   https://drafts.csswg.org/css-fonts-4/#font-weight-numeric-values
+    Weight(Number),
+    /// Normal font weight. Same as 400.
+    Normal,
+    /// Bold font weight. Same as 700.
+    Bold,
+}
+
+impl AbsoluteFontWeight {
+    /// Returns the computed value for this absolute font weight.
+    pub fn compute(&self) -> computed::FontWeight {
+        match *self {
+            AbsoluteFontWeight::Weight(weight) => {
+                computed::FontWeight(
+                    weight.get().max(MIN_FONT_WEIGHT).min(MAX_FONT_WEIGHT)
+                )
+            },
+            AbsoluteFontWeight::Normal => computed::FontWeight::normal(),
+            AbsoluteFontWeight::Bold => computed::FontWeight::bold(),
+        }
+    }
+}
+
+impl Parse for AbsoluteFontWeight {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        if let Ok(number) = input.try(|input| Number::parse(context, input)) {
+            // We could add another AllowedNumericType value, but it doesn't
+            // seem worth it just for a single property with such a weird range,
+            // so we do the clamping here manually.
+            if !number.was_calc() &&
+                (number.get() < MIN_FONT_WEIGHT || number.get() > MAX_FONT_WEIGHT) {
+                return Err(input.new_custom_error(
+                    StyleParseErrorKind::UnspecifiedError
+                ))
+            }
+            return Ok(AbsoluteFontWeight::Weight(number))
+        }
+
+        Ok(try_match_ident_ignore_ascii_case! { input,
+            "normal" => AbsoluteFontWeight::Normal,
+            "bold" => AbsoluteFontWeight::Bold,
+        })
+    }
+}
+
+/// The specified value of the `font-style` property, without the system font
+/// crap.
+pub type SpecifiedFontStyle = generics::FontStyle<Angle>;
+
+impl ToCss for SpecifiedFontStyle {
+    fn to_css<W>(&self, dest: &mut CssWriter<W>) -> fmt::Result
+    where
+        W: Write,
+    {
+        match *self {
+            generics::FontStyle::Normal => dest.write_str("normal"),
+            generics::FontStyle::Italic => dest.write_str("italic"),
+            generics::FontStyle::Oblique(ref angle) => {
+                dest.write_str("oblique")?;
+                if *angle != Self::default_angle() {
+                    dest.write_char(' ')?;
+                    angle.to_css(dest)?;
+                }
+                Ok(())
+            }
+        }
+    }
+}
+
+impl Parse for SpecifiedFontStyle {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        Ok(try_match_ident_ignore_ascii_case! { input,
+            "normal" => generics::FontStyle::Normal,
+            "italic" => generics::FontStyle::Italic,
+            "oblique" => {
+                let angle = input.try(|input| Self::parse_angle(context, input))
+                    .unwrap_or_else(|_| Self::default_angle());
+
+                generics::FontStyle::Oblique(angle)
+            }
+        })
+    }
+}
+
+impl ToComputedValue for SpecifiedFontStyle {
+    type ComputedValue = computed::FontStyle;
+
+    fn to_computed_value(&self, _: &Context) -> Self::ComputedValue {
+        match *self {
+            generics::FontStyle::Normal => generics::FontStyle::Normal,
+            generics::FontStyle::Italic => generics::FontStyle::Italic,
+            generics::FontStyle::Oblique(ref angle) => {
+                generics::FontStyle::Oblique(FontStyleAngle(Self::compute_angle(angle)))
+            }
+        }
+    }
+
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        match *computed {
+            generics::FontStyle::Normal => generics::FontStyle::Normal,
+            generics::FontStyle::Italic => generics::FontStyle::Italic,
+            generics::FontStyle::Oblique(ref angle) => {
+                generics::FontStyle::Oblique(Angle::from_computed_value(&angle.0))
+            }
+        }
+    }
+}
+
+
+/// The default angle for `font-style: oblique`.
+///
+/// NOTE(emilio): As of right now this diverges from the spec, which specifies
+/// 20, because it's not updated yet to account for the resolution in:
+///
+///   https://github.com/w3c/csswg-drafts/issues/2295
+pub const DEFAULT_FONT_STYLE_OBLIQUE_ANGLE_DEGREES: f32 = 14.;
+
+/// From https://drafts.csswg.org/css-fonts-4/#valdef-font-style-oblique-angle:
+///
+///     Values less than -90deg or values greater than 90deg are
+///     invalid and are treated as parse errors.
+///
+/// The maximum angle value that `font-style: oblique` should compute to.
+pub const FONT_STYLE_OBLIQUE_MAX_ANGLE_DEGREES: f32 = 90.;
+
+/// The minimum angle value that `font-style: oblique` should compute to.
+pub const FONT_STYLE_OBLIQUE_MIN_ANGLE_DEGREES: f32 = -90.;
+
+impl SpecifiedFontStyle {
+    /// Gets a clamped angle from a specified Angle.
+    pub fn compute_angle(angle: &Angle) -> ComputedAngle {
+        ComputedAngle::Deg(
+            angle.degrees()
+                .max(FONT_STYLE_OBLIQUE_MIN_ANGLE_DEGREES)
+                .min(FONT_STYLE_OBLIQUE_MAX_ANGLE_DEGREES)
+        )
+    }
+
+    /// Parse a suitable angle for font-style: oblique.
+    pub fn parse_angle<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Angle, ParseError<'i>> {
+        let angle = Angle::parse(context, input)?;
+        if angle.was_calc() {
+            return Ok(angle);
+        }
+
+        let degrees = angle.degrees();
+        if degrees < FONT_STYLE_OBLIQUE_MIN_ANGLE_DEGREES ||
+            degrees > FONT_STYLE_OBLIQUE_MAX_ANGLE_DEGREES
+        {
+            return Err(input.new_custom_error(
+                StyleParseErrorKind::UnspecifiedError
+            ));
+        }
+        return Ok(angle)
+    }
+
+    /// The default angle for `font-style: oblique`.
+    pub fn default_angle() -> Angle {
+        Angle::from_degrees(
+            DEFAULT_FONT_STYLE_OBLIQUE_ANGLE_DEGREES,
+            /* was_calc = */ false,
+        )
+    }
+}
+
+/// The specified value of the `font-style` property.
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss)]
+#[allow(missing_docs)]
+pub enum FontStyle {
+    Specified(SpecifiedFontStyle),
+    System(SystemFont),
+}
+
+impl FontStyle {
+    /// Return the `normal` value.
+    #[inline]
+    pub fn normal() -> Self {
+        FontStyle::Specified(generics::FontStyle::Normal)
+    }
+
+    system_font_methods!(FontStyle, font_style);
+}
+
+impl ToComputedValue for FontStyle {
+    type ComputedValue = computed::FontStyle;
+
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        match *self {
+            FontStyle::Specified(ref specified) => specified.to_computed_value(context),
+            FontStyle::System(..) => self.compute_system(context),
+        }
+    }
+
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        FontStyle::Specified(SpecifiedFontStyle::from_computed_value(computed))
+    }
+}
+
+impl Parse for FontStyle {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        Ok(FontStyle::Specified(SpecifiedFontStyle::parse(context, input)?))
+    }
+}
+
+/// A value for the `font-stretch` property.
+///
+/// https://drafts.csswg.org/css-fonts-4/#font-stretch-prop
+#[allow(missing_docs)]
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq, ToCss)]
+pub enum FontStretch {
+    Stretch(Percentage),
+    Keyword(FontStretchKeyword),
+    System(SystemFont),
+}
+
+/// A keyword value for `font-stretch`.
+#[derive(Clone, Copy, Debug, MallocSizeOf, Parse, PartialEq, ToCss)]
+#[allow(missing_docs)]
+pub enum FontStretchKeyword {
+    Normal,
+    Condensed,
+    UltraCondensed,
+    ExtraCondensed,
+    SemiCondensed,
+    SemiExpanded,
+    Expanded,
+    ExtraExpanded,
+    UltraExpanded,
+}
+
+impl FontStretchKeyword {
+    /// Resolves the value of the keyword as specified in:
+    ///
+    /// https://drafts.csswg.org/css-fonts-4/#font-stretch-prop
+    pub fn compute(&self) -> ComputedPercentage {
+        use self::FontStretchKeyword::*;
+        ComputedPercentage(match *self {
+            UltraCondensed => 0.5,
+            ExtraCondensed => 0.625,
+            Condensed => 0.75,
+            SemiCondensed => 0.875,
+            Normal => 1.,
+            SemiExpanded => 1.125,
+            Expanded => 1.25,
+            ExtraExpanded => 1.5,
+            UltraExpanded => 2.,
+        })
+    }
+
+    /// Does the opposite operation to `compute`, in order to serialize keywords
+    /// if possible.
+    pub fn from_percentage(percentage: f32) -> Option<Self> {
+        use self::FontStretchKeyword::*;
+        // NOTE(emilio): Can't use `match` because of rust-lang/rust#41620.
+        if percentage == 0.5 {
+            return Some(UltraCondensed);
+        }
+        if percentage == 0.625 {
+            return Some(ExtraCondensed);
+        }
+        if percentage == 0.75 {
+            return Some(Condensed);
+        }
+        if percentage == 0.875 {
+            return Some(SemiCondensed);
+        }
+        if percentage == 1. {
+            return Some(Normal);
+        }
+        if percentage == 1.125 {
+            return Some(SemiExpanded);
+        }
+        if percentage == 1.25 {
+            return Some(Expanded);
+        }
+        if percentage == 1.5 {
+            return Some(ExtraExpanded);
+        }
+        if percentage == 2. {
+            return Some(UltraExpanded);
+        }
+        None
+    }
+}
+
+impl FontStretch {
+    /// `normal`.
+    pub fn normal() -> Self {
+        FontStretch::Keyword(FontStretchKeyword::Normal)
+    }
+
+    system_font_methods!(FontStretch, font_stretch);
+}
+
+impl Parse for FontStretch {
+    fn parse<'i, 't>(
+        context: &ParserContext,
+        input: &mut Parser<'i, 't>,
+    ) -> Result<Self, ParseError<'i>> {
+        // From https://drafts.csswg.org/css-fonts-4/#font-stretch-prop:
+        //
+        //    Values less than 0% are not allowed and are treated as parse
+        //    errors.
+        if let Ok(percentage) = input.try(|input| Percentage::parse_non_negative(context, input)) {
+            return Ok(FontStretch::Stretch(percentage));
+        }
+
+        Ok(FontStretch::Keyword(FontStretchKeyword::parse(input)?))
+    }
+}
+
+impl ToComputedValue for FontStretch {
+    type ComputedValue = NonNegative<ComputedPercentage>;
+
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
+        match *self {
+            FontStretch::Stretch(ref percentage) => {
+                NonNegative(percentage.to_computed_value(context))
+            },
+            FontStretch::Keyword(ref kw) => {
+                NonNegative(kw.compute())
+            },
+            FontStretch::System(_) => self.compute_system(context),
+        }
+    }
+
+    fn from_computed_value(computed: &Self::ComputedValue) -> Self {
+        FontStretch::Stretch(Percentage::from_computed_value(&computed.0))
     }
 }
 
@@ -171,19 +542,7 @@ pub enum FontFamily {
 }
 
 impl FontFamily {
-    /// Get `font-family` with system font
-    pub fn system_font(f: SystemFont) -> Self {
-        FontFamily::System(f)
-    }
-
-    /// Get system font
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontFamily::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
+    system_font_methods!(FontFamily, font_family);
 
     /// Parse a specified font-family value
     pub fn parse_specified<'i, 't>(input: &mut Parser<'i, 't>) -> Result<Self, ParseError<'i>> {
@@ -205,19 +564,10 @@ impl FontFamily {
 impl ToComputedValue for FontFamily {
     type ComputedValue = computed::FontFamily;
 
-    fn to_computed_value(&self, _cx: &Context) -> Self::ComputedValue {
+    fn to_computed_value(&self, context: &Context) -> Self::ComputedValue {
         match *self {
             FontFamily::Values(ref v) => computed::FontFamily(v.clone()),
-            FontFamily::System(_) => {
-                #[cfg(feature = "gecko")]
-                {
-                    _cx.cached_system_font.as_ref().unwrap().font_family.clone()
-                }
-                #[cfg(feature = "servo")]
-                {
-                    unreachable!()
-                }
-            },
+            FontFamily::System(_) => self.compute_system(context),
         }
     }
 
@@ -287,19 +637,7 @@ impl FontSizeAdjust {
         FontSizeAdjust::None
     }
 
-    /// Get font-size-adjust with SystemFont
-    pub fn system_font(f: SystemFont) -> Self {
-        FontSizeAdjust::System(f)
-    }
-
-    /// Get SystemFont variant
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontSizeAdjust::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
+    system_font_methods!(FontSizeAdjust, font_size_adjust);
 }
 
 impl ToComputedValue for FontSizeAdjust {
@@ -311,20 +649,7 @@ impl ToComputedValue for FontSizeAdjust {
             FontSizeAdjust::Number(ref n) => {
                 computed::FontSizeAdjust::Number(n.to_computed_value(context))
             },
-            FontSizeAdjust::System(_) => {
-                #[cfg(feature = "gecko")]
-                {
-                    context
-                        .cached_system_font
-                        .as_ref()
-                        .unwrap()
-                        .font_size_adjust
-                }
-                #[cfg(feature = "servo")]
-                {
-                    unreachable!()
-                }
-            },
+            FontSizeAdjust::System(_) => self.compute_system(context),
         }
     }
 
@@ -359,7 +684,7 @@ impl Parse for FontSizeAdjust {
 }
 
 /// Additional information for specified keyword-derived font sizes.
-pub type KeywordInfo = GenericKeywordInfo<NonNegativeLength>;
+pub type KeywordInfo = generics::KeywordInfo<NonNegativeLength>;
 
 impl KeywordInfo {
     /// Computes the final size for this font-size keyword, accounting for
@@ -648,22 +973,10 @@ impl ToComputedValue for FontSize {
 }
 
 impl FontSize {
-    /// Construct a system font value.
-    pub fn system_font(f: SystemFont) -> Self {
-        FontSize::System(f)
-    }
+    system_font_methods!(FontSize);
 
-    /// Obtain the system font, if any
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontSize::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
-
-    #[inline]
     /// Get initial value for specified font size.
+    #[inline]
     pub fn medium() -> Self {
         FontSize::Keyword(KeywordInfo::medium())
     }
@@ -828,42 +1141,16 @@ impl FontVariantAlternates {
         FontVariantAlternates::Value(VariantAlternatesList(vec![].into_boxed_slice()))
     }
 
-    /// Get FontVariantAlternates with system font
-    pub fn system_font(f: SystemFont) -> Self {
-        FontVariantAlternates::System(f)
-    }
-
-    /// Get SystemFont of FontVariantAlternates
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontVariantAlternates::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
+    system_font_methods!(FontVariantAlternates, font_variant_alternates);
 }
 
 impl ToComputedValue for FontVariantAlternates {
     type ComputedValue = computed::FontVariantAlternates;
 
-    fn to_computed_value(&self, _context: &Context) -> computed::FontVariantAlternates {
+    fn to_computed_value(&self, context: &Context) -> computed::FontVariantAlternates {
         match *self {
             FontVariantAlternates::Value(ref v) => v.clone(),
-            FontVariantAlternates::System(_) => {
-                #[cfg(feature = "gecko")]
-                {
-                    _context
-                        .cached_system_font
-                        .as_ref()
-                        .unwrap()
-                        .font_variant_alternates
-                        .clone()
-                }
-                #[cfg(feature = "servo")]
-                {
-                    unreachable!()
-                }
-            },
+            FontVariantAlternates::System(_) => self.compute_system(context),
         }
     }
 
@@ -1105,42 +1392,16 @@ impl FontVariantEastAsian {
         FontVariantEastAsian::Value(VariantEastAsian::empty())
     }
 
-    /// Get `font-variant-east-asian` with system font
-    pub fn system_font(f: SystemFont) -> Self {
-        FontVariantEastAsian::System(f)
-    }
-
-    /// Get system font
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontVariantEastAsian::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
+    system_font_methods!(FontVariantEastAsian, font_variant_east_asian);
 }
 
 impl ToComputedValue for FontVariantEastAsian {
     type ComputedValue = computed::FontVariantEastAsian;
 
-    fn to_computed_value(&self, _context: &Context) -> computed::FontVariantEastAsian {
+    fn to_computed_value(&self, context: &Context) -> computed::FontVariantEastAsian {
         match *self {
             FontVariantEastAsian::Value(ref v) => v.clone(),
-            FontVariantEastAsian::System(_) => {
-                #[cfg(feature = "gecko")]
-                {
-                    _context
-                        .cached_system_font
-                        .as_ref()
-                        .unwrap()
-                        .font_variant_east_asian
-                        .clone()
-                }
-                #[cfg(feature = "servo")]
-                {
-                    unreachable!()
-                }
-            },
+            FontVariantEastAsian::System(_) => self.compute_system(context),
         }
     }
 
@@ -1351,22 +1612,10 @@ pub enum FontVariantLigatures {
 }
 
 impl FontVariantLigatures {
-    /// Get `font-variant-ligatures` with system font
-    pub fn system_font(f: SystemFont) -> Self {
-        FontVariantLigatures::System(f)
-    }
+    system_font_methods!(FontVariantLigatures, font_variant_ligatures);
 
-    /// Get system font
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontVariantLigatures::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
-
-    #[inline]
     /// Default value of `font-variant-ligatures` as `empty`
+    #[inline]
     pub fn empty() -> FontVariantLigatures {
         FontVariantLigatures::Value(VariantLigatures::empty())
     }
@@ -1381,24 +1630,10 @@ impl FontVariantLigatures {
 impl ToComputedValue for FontVariantLigatures {
     type ComputedValue = computed::FontVariantLigatures;
 
-    fn to_computed_value(&self, _context: &Context) -> computed::FontVariantLigatures {
+    fn to_computed_value(&self, context: &Context) -> computed::FontVariantLigatures {
         match *self {
             FontVariantLigatures::Value(ref v) => v.clone(),
-            FontVariantLigatures::System(_) => {
-                #[cfg(feature = "gecko")]
-                {
-                    _context
-                        .cached_system_font
-                        .as_ref()
-                        .unwrap()
-                        .font_variant_ligatures
-                        .clone()
-                }
-                #[cfg(feature = "servo")]
-                {
-                    unreachable!()
-                }
-            },
+            FontVariantLigatures::System(_) => self.compute_system(context),
         }
     }
 
@@ -1611,42 +1846,16 @@ impl FontVariantNumeric {
         FontVariantNumeric::Value(VariantNumeric::empty())
     }
 
-    /// Get `font-variant-numeric` with system font
-    pub fn system_font(f: SystemFont) -> Self {
-        FontVariantNumeric::System(f)
-    }
-
-    /// Get system font
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontVariantNumeric::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
+    system_font_methods!(FontVariantNumeric, font_variant_numeric);
 }
 
 impl ToComputedValue for FontVariantNumeric {
     type ComputedValue = computed::FontVariantNumeric;
 
-    fn to_computed_value(&self, _context: &Context) -> computed::FontVariantNumeric {
+    fn to_computed_value(&self, context: &Context) -> computed::FontVariantNumeric {
         match *self {
             FontVariantNumeric::Value(ref v) => v.clone(),
-            FontVariantNumeric::System(_) => {
-                #[cfg(feature = "gecko")]
-                {
-                    _context
-                        .cached_system_font
-                        .as_ref()
-                        .unwrap()
-                        .font_variant_numeric
-                        .clone()
-                }
-                #[cfg(feature = "servo")]
-                {
-                    unreachable!()
-                }
-            },
+            FontVariantNumeric::System(_) => self.compute_system(context),
         }
     }
 
@@ -1744,19 +1953,7 @@ impl FontFeatureSettings {
         FontFeatureSettings::Value(FontSettings::normal())
     }
 
-    /// Get `font-feature-settings` with system font
-    pub fn system_font(f: SystemFont) -> Self {
-        FontFeatureSettings::System(f)
-    }
-
-    /// Get system font
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontFeatureSettings::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
+    system_font_methods!(FontFeatureSettings, font_feature_settings);
 }
 
 impl ToComputedValue for FontFeatureSettings {
@@ -1765,21 +1962,7 @@ impl ToComputedValue for FontFeatureSettings {
     fn to_computed_value(&self, context: &Context) -> computed::FontFeatureSettings {
         match *self {
             FontFeatureSettings::Value(ref v) => v.to_computed_value(context),
-            FontFeatureSettings::System(_) => {
-                #[cfg(feature = "gecko")]
-                {
-                    context
-                        .cached_system_font
-                        .as_ref()
-                        .unwrap()
-                        .font_feature_settings
-                        .clone()
-                }
-                #[cfg(feature = "servo")]
-                {
-                    unreachable!()
-                }
-            },
+            FontFeatureSettings::System(_) => self.compute_system(context),
         }
     }
 
@@ -1919,26 +2102,14 @@ impl FontLanguageOverride {
         FontLanguageOverride::Normal
     }
 
-    /// Get `font-language-override` with `system font`
-    pub fn system_font(f: SystemFont) -> Self {
-        FontLanguageOverride::System(f)
-    }
-
-    /// Get system font
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontLanguageOverride::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
+    system_font_methods!(FontLanguageOverride, font_language_override);
 }
 
 impl ToComputedValue for FontLanguageOverride {
     type ComputedValue = computed::FontLanguageOverride;
 
     #[inline]
-    fn to_computed_value(&self, _context: &Context) -> computed::FontLanguageOverride {
+    fn to_computed_value(&self, context: &Context) -> computed::FontLanguageOverride {
         match *self {
             FontLanguageOverride::Normal => computed::FontLanguageOverride(0),
             FontLanguageOverride::Override(ref lang) => {
@@ -1952,20 +2123,7 @@ impl ToComputedValue for FontLanguageOverride {
                 let bytes = computed_lang.into_bytes();
                 computed::FontLanguageOverride(BigEndian::read_u32(&bytes))
             },
-            FontLanguageOverride::System(_) => {
-                #[cfg(feature = "gecko")]
-                {
-                    _context
-                        .cached_system_font
-                        .as_ref()
-                        .unwrap()
-                        .font_language_override
-                }
-                #[cfg(feature = "servo")]
-                {
-                    unreachable!()
-                }
-            },
+            FontLanguageOverride::System(_) => self.compute_system(context),
         }
     }
     #[inline]
@@ -2026,19 +2184,7 @@ impl FontVariationSettings {
         FontVariationSettings::Value(FontSettings::normal())
     }
 
-    /// Get `font-variation-settings` with system font
-    pub fn system_font(f: SystemFont) -> Self {
-        FontVariationSettings::System(f)
-    }
-
-    /// Get system font
-    pub fn get_system(&self) -> Option<SystemFont> {
-        if let FontVariationSettings::System(s) = *self {
-            Some(s)
-        } else {
-            None
-        }
-    }
+    system_font_methods!(FontVariationSettings, font_variation_settings);
 }
 
 impl ToComputedValue for FontVariationSettings {
@@ -2047,21 +2193,7 @@ impl ToComputedValue for FontVariationSettings {
     fn to_computed_value(&self, context: &Context) -> computed::FontVariationSettings {
         match *self {
             FontVariationSettings::Value(ref v) => v.to_computed_value(context),
-            FontVariationSettings::System(_) => {
-                #[cfg(feature = "gecko")]
-                {
-                    context
-                        .cached_system_font
-                        .as_ref()
-                        .unwrap()
-                        .font_variation_settings
-                        .clone()
-                }
-                #[cfg(feature = "servo")]
-                {
-                    unreachable!()
-                }
-            },
+            FontVariationSettings::System(_) => self.compute_system(context),
         }
     }
 
diff --git a/components/style/values/specified/mod.rs b/components/style/values/specified/mod.rs
index 570651ea2ef..20b49596ab7 100644
--- a/components/style/values/specified/mod.rs
+++ b/components/style/values/specified/mod.rs
@@ -34,8 +34,8 @@ pub use self::border::{BorderCornerRadius, BorderImageSlice, BorderImageWidth};
 pub use self::border::{BorderImageRepeat, BorderImageSideWidth};
 pub use self::border::{BorderRadius, BorderSideWidth, BorderSpacing};
 pub use self::column::ColumnCount;
-pub use self::font::{FontSize, FontSizeAdjust, FontSynthesis, FontVariantAlternates, FontWeight};
-pub use self::font::{FontFamily, FontLanguageOverride, FontVariantEastAsian, FontVariationSettings};
+pub use self::font::{FontSize, FontSizeAdjust, FontStretch, FontSynthesis, FontVariantAlternates, FontWeight};
+pub use self::font::{FontFamily, FontLanguageOverride, FontStyle, FontVariantEastAsian, FontVariationSettings};
 pub use self::font::{FontFeatureSettings, FontVariantLigatures, FontVariantNumeric};
 pub use self::font::{MozScriptLevel, MozScriptMinSize, MozScriptSizeMultiplier, XLang, XTextZoom};
 pub use self::box_::{AnimationIterationCount, AnimationName, Contain, Display};
@@ -201,7 +201,14 @@ impl Number {
         }
     }
 
+    /// Returns whether this number came from a `calc()` expression.
+    #[inline]
+    pub fn was_calc(&self) -> bool {
+        self.calc_clamping_mode.is_some()
+    }
+
     /// Returns the numeric value, clamped if needed.
+    #[inline]
     pub fn get(&self) -> f32 {
         self.calc_clamping_mode
             .map_or(self.value, |mode| mode.clamp(self.value))
diff --git a/etc/ci/buildbot_steps.yml b/etc/ci/buildbot_steps.yml
index 12ba8a4b876..217c409b27b 100644
--- a/etc/ci/buildbot_steps.yml
+++ b/etc/ci/buildbot_steps.yml
@@ -22,7 +22,6 @@ mac-rel-wpt2:
   - env PKG_CONFIG_PATH=/usr/local/opt/zlib/lib/pkgconfig ./mach build --release
   - ./mach test-wpt --release --processes 4 --total-chunks 6 --this-chunk 2 --log-raw test-wpt.log --log-errorsummary wpt-errorsummary.log --always-succeed
   - ./mach filter-intermittents wpt-errorsummary.log --log-intermittents intermittents.log --log-filteredsummary filtered-wpt-errorsummary.log --tracker-api default --reporter-api default
-  - env PKG_CONFIG_PATH=/usr/local/opt/zlib/lib/pkgconfig ./mach build-geckolib --release
 
 mac-rel-wpt3:
   - ./mach clean-nightlies --keep 3 --force
@@ -47,7 +46,6 @@ mac-dev-unit:
   - env PKG_CONFIG_PATH=/usr/local/opt/zlib/lib/pkgconfig ./mach test-unit
   - python ./etc/memory_reports_over_time.py --test
   - ./mach package --dev
-  - ./mach build-geckolib
   - bash ./etc/ci/lockfile_changed.sh
   - bash ./etc/ci/manifest_changed.sh
 
@@ -113,8 +111,6 @@ linux-dev:
     - python ./etc/memory_reports_over_time.py --test
     - ./mach package --dev
     - ./mach build --dev --no-default-features --features default-except-unstable
-    - ./mach build-geckolib
-    - ./mach test-stylo
     - bash ./etc/ci/lockfile_changed.sh
     - bash ./etc/ci/manifest_changed.sh
     - bash ./etc/ci/check_no_panic.sh
@@ -145,8 +141,6 @@ linux-rel-css:
     - ./mach build --release --with-debug-assertions
     - ./mach test-wpt --release --processes 24 --total-chunks 2 --this-chunk 2 --log-raw test-wpt.log --log-errorsummary wpt-errorsummary.log --always-succeed
     - ./mach filter-intermittents wpt-errorsummary.log --log-intermittents intermittents.log --log-filteredsummary filtered-wpt-errorsummary.log --tracker-api default --reporter-api default
-    - ./mach build-geckolib --release
-    - ./mach test-stylo --release
     - bash ./etc/ci/lockfile_changed.sh
     - bash ./etc/ci/manifest_changed.sh
     - ./etc/ci/clean_build_artifacts.sh
@@ -201,8 +195,6 @@ windows-msvc-dev:
   - mach.bat build --dev
   - mach.bat test-unit
   - mach.bat package --dev
-  - mach.bat build-geckolib
-  - mach.bat test-stylo
 
 windows-msvc-nightly:
   env:
diff --git a/etc/ci/taskcluster-test.sh b/etc/ci/taskcluster-test.sh
index 0ef6863004f..9a18b9a489a 100755
--- a/etc/ci/taskcluster-test.sh
+++ b/etc/ci/taskcluster-test.sh
@@ -15,8 +15,6 @@ env CC=gcc-5 CXX=g++-5 ./mach build --dev
 env ./mach test-unit
 env ./mach package --dev
 env ./mach build --dev --no-default-features --features default-except-unstable
-./mach build-geckolib
-./mach test-stylo
 bash ./etc/ci/lockfile_changed.sh
 bash ./etc/ci/manifest_changed.sh
 bash ./etc/ci/check_no_panic.sh
diff --git a/etc/ci/upload_docs.sh b/etc/ci/upload_docs.sh
index 5a8188df2de..f1cfa076d0c 100755
--- a/etc/ci/upload_docs.sh
+++ b/etc/ci/upload_docs.sh
@@ -23,11 +23,6 @@ env CC=gcc-5 CXX=g++-5 ./mach doc
 # when it encounters directories.
 cp -r etc/doc.servo.org/* target/doc/
 
-./mach cargo-geckolib doc
-# Use recursive copy here to avoid `cp` returning an error code
-# when it encounters directories.
-cp -r target/geckolib/doc/* target/doc/geckolib/
-
 python components/style/properties/build.py servo html regular
 
 cd components/script
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index 3a476640de1..04d5a22cd40 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -6,6 +6,7 @@ use cssparser::{ParseErrorKind, Parser, ParserInput, SourceLocation};
 use cssparser::ToCss as ParserToCss;
 use env_logger::Builder;
 use malloc_size_of::MallocSizeOfOps;
+use nsstring::nsCString;
 use selectors::{NthIndexCache, SelectorList};
 use selectors::matching::{MatchingContext, MatchingMode, matches_selector};
 use servo_arc::{Arc, ArcBorrow, RawOffsetArc};
@@ -92,7 +93,8 @@ use style::gecko_bindings::structs;
 use style::gecko_bindings::structs::{CallerType, CSSPseudoElementType, CompositeOperation};
 use style::gecko_bindings::structs::{Loader, LoaderReusableStyleSheets};
 use style::gecko_bindings::structs::{RawServoStyleRule, ComputedStyleStrong, RustString};
-use style::gecko_bindings::structs::{ServoStyleSheet, SheetLoadData, SheetParsingMode, nsAtom, nsCSSPropertyID};
+use style::gecko_bindings::structs::{ServoStyleSheet, SheetLoadData, SheetLoadDataHolder};
+use style::gecko_bindings::structs::{SheetParsingMode, nsAtom, nsCSSPropertyID};
 use style::gecko_bindings::structs::{nsCSSFontDesc, nsCSSCounterDesc};
 use style::gecko_bindings::structs::{nsRestyleHint, nsChangeHint, PropertyValuePair};
 use style::gecko_bindings::structs::AtomArray;
@@ -145,6 +147,7 @@ use style::stylesheets::{DocumentRule, FontFaceRule, FontFeatureValuesRule, Impo
 use style::stylesheets::{KeyframesRule, MediaRule, NamespaceRule, Origin, OriginSet, PageRule};
 use style::stylesheets::{StyleRule, StylesheetContents, SupportsRule};
 use style::stylesheets::StylesheetLoader as StyleStylesheetLoader;
+use style::stylesheets::import_rule::ImportSheet;
 use style::stylesheets::keyframes_rule::{Keyframe, KeyframeSelector, KeyframesStepValue};
 use style::stylesheets::supports_rule::parse_condition_or_declaration;
 use style::stylist::{add_size_of_ua_cache, AuthorStylesEnabled, RuleInclusion, Stylist};
@@ -163,7 +166,7 @@ use style::values::specified::gecko::{IntersectionObserverRootMargin, PixelOrPer
 use style::values::specified::source_size_list::SourceSizeList;
 use style_traits::{CssWriter, ParsingMode, StyleParseErrorKind, ToCss};
 use super::error_reporter::ErrorReporter;
-use super::stylesheet_loader::StylesheetLoader;
+use super::stylesheet_loader::{AsyncStylesheetParser, StylesheetLoader};
 
 /*
  * For Gecko->Servo function calls, we need to redeclare the same signature that was declared in
@@ -1122,6 +1125,15 @@ pub extern "C" fn Servo_StyleSheet_Empty(mode: SheetParsingMode) -> RawServoStyl
     ).into_strong()
 }
 
+fn mode_to_origin(mode: SheetParsingMode) -> Origin {
+    match mode {
+        SheetParsingMode::eAuthorSheetFeatures => Origin::Author,
+        SheetParsingMode::eUserSheetFeatures => Origin::User,
+        SheetParsingMode::eAgentSheetFeatures => Origin::UserAgent,
+        SheetParsingMode::eSafeAgentSheetFeatures => Origin::UserAgent,
+    }
+}
+
 /// Note: The load_data corresponds to this sheet, and is passed as the parent
 /// load data for child sheet loads. It may be null for certain cases where we
 /// know we won't have child loads.
@@ -1130,8 +1142,7 @@ pub extern "C" fn Servo_StyleSheet_FromUTF8Bytes(
     loader: *mut Loader,
     stylesheet: *mut ServoStyleSheet,
     load_data: *mut SheetLoadData,
-    data: *const u8,
-    data_len: usize,
+    bytes: *const nsACString,
     mode: SheetParsingMode,
     extra_data: *mut URLExtraData,
     line_number_offset: u32,
@@ -1139,14 +1150,7 @@ pub extern "C" fn Servo_StyleSheet_FromUTF8Bytes(
     reusable_sheets: *mut LoaderReusableStyleSheets,
 ) -> RawServoStyleSheetContentsStrong {
     let global_style_data = &*GLOBAL_STYLE_DATA;
-    let input = unsafe { ::std::str::from_utf8_unchecked(::std::slice::from_raw_parts(data, data_len)) };
-
-    let origin = match mode {
-        SheetParsingMode::eAuthorSheetFeatures => Origin::Author,
-        SheetParsingMode::eUserSheetFeatures => Origin::User,
-        SheetParsingMode::eAgentSheetFeatures => Origin::UserAgent,
-        SheetParsingMode::eSafeAgentSheetFeatures => Origin::UserAgent,
-    };
+    let input: &str = unsafe { (*bytes).as_str_unchecked() };
 
     let reporter = ErrorReporter::new(stylesheet, loader, extra_data);
     let url_data = unsafe { RefPtr::from_ptr_ref(&extra_data) };
@@ -1164,12 +1168,44 @@ pub extern "C" fn Servo_StyleSheet_FromUTF8Bytes(
 
 
     Arc::new(StylesheetContents::from_str(
-        input, url_data.clone(), origin,
+        input, url_data.clone(), mode_to_origin(mode),
         &global_style_data.shared_lock, loader, &reporter,
         quirks_mode.into(), line_number_offset)
     ).into_strong()
 }
 
+#[no_mangle]
+pub extern "C" fn Servo_StyleSheet_FromUTF8BytesAsync(
+    load_data: *mut SheetLoadDataHolder,
+    extra_data: *mut URLExtraData,
+    bytes: *const nsACString,
+    mode: SheetParsingMode,
+    line_number_offset: u32,
+    quirks_mode: nsCompatibility,
+) {
+    let (load_data, extra_data, bytes) = unsafe {
+        let mut b = nsCString::new();
+        b.assign(&*bytes);
+        (RefPtr::new(load_data), RefPtr::new(extra_data), b)
+    };
+    let async_parser = AsyncStylesheetParser::new(
+        load_data,
+        extra_data,
+        bytes,
+        mode_to_origin(mode),
+        quirks_mode.into(),
+        line_number_offset
+    );
+
+    if let Some(thread_pool) = STYLE_THREAD_POOL.style_thread_pool.as_ref() {
+        thread_pool.spawn(|| {
+            async_parser.parse();
+        });
+    } else {
+        async_parser.parse();
+    }
+}
+
 #[no_mangle]
 pub extern "C" fn Servo_StyleSet_AppendStyleSheet(
     raw_data: RawServoStyleSetBorrowed,
@@ -2052,6 +2088,17 @@ pub extern "C" fn Servo_ImportRule_GetSheet(
     })
 }
 
+#[no_mangle]
+pub extern "C" fn Servo_ImportRule_SetSheet(
+    rule: RawServoImportRuleBorrowed,
+    sheet: *mut ServoStyleSheet,
+) {
+    write_locked_arc(rule, |rule: &mut ImportRule| {
+        let sheet = unsafe { GeckoStyleSheet::new(sheet) };
+        rule.stylesheet = ImportSheet::new(sheet);
+    })
+}
+
 #[no_mangle]
 pub extern "C" fn Servo_Keyframe_GetKeyText(
     keyframe: RawServoKeyframeBorrowed,
@@ -2709,7 +2756,7 @@ pub unsafe extern "C" fn Servo_ComputedValues_GetForAnonymousBox(
                 let level = match origin {
                     Origin::UserAgent => CascadeLevel::UANormal,
                     Origin::User => CascadeLevel::UserNormal,
-                    Origin::Author => CascadeLevel::AuthorNormal,
+                    Origin::Author => CascadeLevel::SameTreeAuthorNormal,
                 };
                 for rule in data.pages.iter() {
                     declarations.push(ApplicableDeclarationBlock::from_declarations(
@@ -3753,6 +3800,7 @@ pub extern "C" fn Servo_DeclarationBlock_SetKeywordValue(
 ) {
     use style::properties::{PropertyDeclaration, LonghandId};
     use style::properties::longhands;
+    use style::values::generics::font::FontStyle;
     use style::values::specified::BorderStyle;
 
     let long = get_longhand_from_id!(property);
@@ -3773,7 +3821,14 @@ pub extern "C" fn Servo_DeclarationBlock_SetKeywordValue(
             longhands::font_size::SpecifiedValue::from_html_size(value as u8)
         },
         FontStyle => {
-            ToComputedValue::from_computed_value(&longhands::font_style::computed_value::T::from_gecko_keyword(value))
+            let val = if value == structs::NS_FONT_STYLE_ITALIC {
+                FontStyle::Italic
+            } else {
+                debug_assert_eq!(value, structs::NS_FONT_STYLE_NORMAL);
+                FontStyle::Normal
+            };
+
+            ToComputedValue::from_computed_value(&val)
         },
         FontWeight => longhands::font_weight::SpecifiedValue::from_gecko_keyword(value),
         ListStyleType => Box::new(longhands::list_style_type::SpecifiedValue::from_gecko_keyword(value)),
@@ -5360,9 +5415,9 @@ pub extern "C" fn Servo_ParseFontShorthandForMatching(
     stretch: nsCSSValueBorrowedMut,
     weight: nsCSSValueBorrowedMut
 ) -> bool {
-    use style::properties::longhands::{font_stretch, font_style};
     use style::properties::shorthands::font;
-    use style::values::specified::font::{FontFamily, FontWeight};
+    use style::values::generics::font::FontStyle as GenericFontStyle;
+    use style::values::specified::font::{FontFamily, FontWeight, FontStyle, SpecifiedFontStyle};
 
     let string = unsafe { (*value).to_string() };
     let mut input = ParserInput::new(&string);
@@ -5387,18 +5442,26 @@ pub extern "C" fn Servo_ParseFontShorthandForMatching(
         FontFamily::Values(list) => family.set_move(list.0),
         FontFamily::System(_) => return false,
     }
-    style.set_from(match font.font_style {
-        font_style::SpecifiedValue::Keyword(ref kw) => kw,
-        font_style::SpecifiedValue::System(_) => return false,
-    });
-    stretch.set_from(match font.font_stretch {
-        font_stretch::SpecifiedValue::Keyword(ref kw) => kw,
-        font_stretch::SpecifiedValue::System(_) => return false,
-    });
+
+    let specified_font_style = match font.font_style {
+        FontStyle::Specified(ref s) => s,
+        FontStyle::System(_) => return false,
+    };
+    match *specified_font_style {
+        GenericFontStyle::Normal => style.set_normal(),
+        GenericFontStyle::Italic => style.set_enum(structs::NS_FONT_STYLE_ITALIC as i32),
+        GenericFontStyle::Oblique(ref angle) => {
+            style.set_font_style(SpecifiedFontStyle::compute_angle(angle).degrees())
+        }
+    }
+
+    if font.font_stretch.get_system().is_some() {
+        return false;
+    }
+    stretch.set_from(&font.font_stretch);
+
     match font.font_weight {
-        FontWeight::Weight(w) => weight.set_from(w),
-        FontWeight::Normal => weight.set_enum(structs::NS_FONT_WEIGHT_NORMAL as i32),
-        FontWeight::Bold => weight.set_enum(structs::NS_FONT_WEIGHT_BOLD as i32),
+        FontWeight::Absolute(w) => weight.set_font_weight(w.compute().0),
         // Resolve relative font weights against the initial of font-weight
         // (normal, which is equivalent to 400).
         FontWeight::Bolder => weight.set_enum(structs::NS_FONT_WEIGHT_BOLD as i32),
diff --git a/ports/geckolib/lib.rs b/ports/geckolib/lib.rs
index 80c22e54707..d48a096df64 100644
--- a/ports/geckolib/lib.rs
+++ b/ports/geckolib/lib.rs
@@ -9,6 +9,7 @@ extern crate env_logger;
 extern crate libc;
 #[macro_use] extern crate log;
 extern crate malloc_size_of;
+extern crate nsstring;
 extern crate selectors;
 extern crate servo_arc;
 extern crate smallvec;
diff --git a/ports/geckolib/stylesheet_loader.rs b/ports/geckolib/stylesheet_loader.rs
index 1dfe30e8bdb..0c320fee897 100644
--- a/ports/geckolib/stylesheet_loader.rs
+++ b/ports/geckolib/stylesheet_loader.rs
@@ -3,15 +3,24 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use cssparser::SourceLocation;
+use nsstring::nsCString;
 use servo_arc::Arc;
+use style::context::QuirksMode;
+use style::error_reporting::NullReporter;
 use style::gecko::data::GeckoStyleSheet;
+use style::gecko::global_style_data::GLOBAL_STYLE_DATA;
+use style::gecko_bindings::bindings;
 use style::gecko_bindings::bindings::Gecko_LoadStyleSheet;
-use style::gecko_bindings::structs::{Loader, ServoStyleSheet, SheetLoadData, LoaderReusableStyleSheets};
+use style::gecko_bindings::structs::{Loader, LoaderReusableStyleSheets};
+use style::gecko_bindings::structs::{ServoStyleSheet, SheetLoadData, SheetLoadDataHolder};
+use style::gecko_bindings::structs::URLExtraData;
 use style::gecko_bindings::sugar::ownership::FFIArcHelpers;
+use style::gecko_bindings::sugar::refptr::RefPtr;
 use style::media_queries::MediaList;
 use style::parser::ParserContext;
 use style::shared_lock::{Locked, SharedRwLock};
-use style::stylesheets::{ImportRule, StylesheetLoader as StyleStylesheetLoader};
+use style::stylesheets::{ImportRule, Origin, StylesheetLoader as StyleStylesheetLoader};
+use style::stylesheets::StylesheetContents;
 use style::stylesheets::import_rule::ImportSheet;
 use style::values::CssUrl;
 
@@ -41,15 +50,11 @@ impl StyleStylesheetLoader for StylesheetLoader {
         // so this raw pointer will still be valid.
 
         let child_sheet = unsafe {
-            let (spec_bytes, spec_len) = url.as_slice_components();
-            let base_url_data = url.extra_data.get();
             Gecko_LoadStyleSheet(self.0,
                                  self.1,
                                  self.2,
                                  self.3,
-                                 base_url_data,
-                                 spec_bytes,
-                                 spec_len as u32,
+                                 url.for_ffi(),
                                  media.into_strong())
         };
 
@@ -60,3 +65,75 @@ impl StyleStylesheetLoader for StylesheetLoader {
         Arc::new(lock.wrap(ImportRule { url, source_location, stylesheet }))
     }
 }
+
+pub struct AsyncStylesheetParser {
+    load_data: RefPtr<SheetLoadDataHolder>,
+    extra_data: RefPtr<URLExtraData>,
+    bytes: nsCString,
+    origin: Origin,
+    quirks_mode: QuirksMode,
+    line_number_offset: u32,
+}
+
+impl AsyncStylesheetParser {
+    pub fn new(
+        load_data: RefPtr<SheetLoadDataHolder>,
+        extra_data: RefPtr<URLExtraData>,
+        bytes: nsCString,
+        origin: Origin,
+        quirks_mode: QuirksMode,
+        line_number_offset: u32,
+    ) -> Self {
+        AsyncStylesheetParser {
+            load_data,
+            extra_data,
+            bytes,
+            origin,
+            quirks_mode,
+            line_number_offset,
+        }
+    }
+
+    pub fn parse(self) {
+        let global_style_data = &*GLOBAL_STYLE_DATA;
+        let input: &str = unsafe { (*self.bytes).as_str_unchecked() };
+
+        // Note: Parallel CSS parsing doesn't report CSS errors. When errors
+        // are being logged, Gecko prevents the parallel parsing path from
+        // running.
+        let sheet = Arc::new(StylesheetContents::from_str(
+            input, self.extra_data.clone(), self.origin,
+            &global_style_data.shared_lock, Some(&self), &NullReporter,
+            self.quirks_mode.into(), self.line_number_offset)
+        );
+
+        unsafe {
+            bindings::Gecko_StyleSheet_FinishAsyncParse(self.load_data.get(), sheet.into_strong());
+        }
+    }
+}
+
+impl StyleStylesheetLoader for AsyncStylesheetParser {
+    fn request_stylesheet(
+        &self,
+        url: CssUrl,
+        source_location: SourceLocation,
+        _context: &ParserContext,
+        lock: &SharedRwLock,
+        media: Arc<Locked<MediaList>>,
+    ) -> Arc<Locked<ImportRule>> {
+        let stylesheet = ImportSheet::new_pending(self.origin, self.quirks_mode);
+        let rule = Arc::new(lock.wrap(ImportRule { url: url.clone(), source_location, stylesheet }));
+
+        unsafe {
+            bindings::Gecko_LoadStyleSheetAsync(
+                self.load_data.get(),
+                url.for_ffi(),
+                media.into_strong(),
+                rule.clone().into_strong()
+            );
+        }
+
+        rule
+    }
+}
diff --git a/ports/geckolib/tests/build.rs b/ports/geckolib/tests/build.rs
index ab21e2186cd..7feb9d10405 100644
--- a/ports/geckolib/tests/build.rs
+++ b/ports/geckolib/tests/build.rs
@@ -11,8 +11,11 @@ use std::io::{BufRead, BufReader, Write};
 use std::path::Path;
 
 fn main() {
+    // https://github.com/rust-lang/cargo/issues/3544
+    let style_out_dir = env::var_os("DEP_FOR SOME REASON THE LINKS KEY IS REQUIRED \
+                                     TO PASS DATA AROUND BETWEEN BUILD SCRIPTS_OUT_DIR").unwrap();
     let root_path = Path::new("../../../");
-    let bindings_file = root_path.join("components/style/gecko/generated/bindings.rs");
+    let bindings_file = Path::new(&style_out_dir).join("gecko/bindings.rs");
     let glue_file = root_path.join("ports/geckolib/glue.rs");
 
     println!("cargo:rerun-if-changed=build.rs");
@@ -70,9 +73,6 @@ fn main() {
         }
     }
 
-    // https://github.com/rust-lang/cargo/issues/3544
-    let style_out_dir = env::var_os("DEP_FOR SOME REASON THE LINKS KEY IS REQUIRED \
-                                     TO PASS DATA AROUND BETWEEN BUILD SCRIPTS_OUT_DIR").unwrap();
     File::create(out_dir.join("bindings.rs"))
         .unwrap()
         .write_all(format!("include!(concat!({:?}, \"/gecko/structs.rs\"));",
diff --git a/tests/unit/style/parsing/font.rs b/tests/unit/style/parsing/font.rs
deleted file mode 100644
index b111ceae8bc..00000000000
--- a/tests/unit/style/parsing/font.rs
+++ /dev/null
@@ -1,17 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-use parsing::parse;
-use style::properties::longhands::font_weight;
-
-#[test]
-fn font_weight_keyword_should_preserve_keyword() {
-    use style::properties::longhands::font_weight::SpecifiedValue;
-
-    let result = parse(font_weight::parse, "normal").unwrap();
-    assert_eq!(result, SpecifiedValue::Normal);
-
-    let result = parse(font_weight::parse, "bold").unwrap();
-    assert_eq!(result, SpecifiedValue::Bold);
-}
diff --git a/tests/unit/style/parsing/mod.rs b/tests/unit/style/parsing/mod.rs
index 1c1dfc3d185..d89e76378f7 100644
--- a/tests/unit/style/parsing/mod.rs
+++ b/tests/unit/style/parsing/mod.rs
@@ -109,7 +109,6 @@ mod border;
 mod box_;
 mod column;
 mod effects;
-mod font;
 mod image;
 mod inherited_text;
 mod length;
diff --git a/tests/wpt/metadata/css/css-fonts/variations/font-parse-numeric-stretch-style-weight.html.ini b/tests/wpt/metadata/css/css-fonts/variations/font-parse-numeric-stretch-style-weight.html.ini
index 1d94b9c3350..ce924174648 100644
--- a/tests/wpt/metadata/css/css-fonts/variations/font-parse-numeric-stretch-style-weight.html.ini
+++ b/tests/wpt/metadata/css/css-fonts/variations/font-parse-numeric-stretch-style-weight.html.ini
@@ -1,36 +1,4 @@
 [font-parse-numeric-stretch-style-weight.html]
-  [Valid value 850 for font property weight used for styling.]
-    expected: FAIL
-
-  [Valid value 850.3 for font property weight used for styling.]
-    expected: FAIL
-
-  [Valid value calc(100 + 300) for font property weight used for styling.]
-    expected: FAIL
-
-  [Valid value calc(0.2 + 205.5) for font property weight used for styling.]
-    expected: FAIL
-
-  [Valid value 51% for font property stretch used for styling.]
-    expected: FAIL
-
-  [Valid value 199% for font property stretch used for styling.]
-    expected: FAIL
-
-  [Valid value calc(10% + 20%) for font property stretch used for styling.]
-    expected: FAIL
-
-  [Valid value oblique 50deg for font property style used for styling.]
-    expected: FAIL
-
-  [Valid value oblique -90deg for font property style used for styling.]
-    expected: FAIL
-
-  [Valid value oblique 90deg for font property style used for styling.]
-    expected: FAIL
-
-  [Valid value oblique calc(30deg + 20deg) for font property style used for styling.]
-    expected: FAIL
 
   [Valid value 100 matches 100 for weight in @font-face.]
     expected: FAIL
@@ -188,18 +156,6 @@
   [Value italic 90deg must not be accepted as style in @font-face.]
     expected: FAIL
 
-  [Valid value calc(0 - 100) for font property weight used for styling.]
-    expected: FAIL
-
-  [Valid value calc(200 + 801) for font property weight used for styling.]
-    expected: FAIL
-
-  [Valid value 0% for font property stretch used for styling.]
-    expected: FAIL
-
-  [Valid value oblique calc(90deg + 20deg) for font property style used for styling.]
-    expected: FAIL
-
   [Valid value 500 400 matches 500 400 for weight in @font-face.]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/css/css-fonts/variations/font-shorthand.html.ini b/tests/wpt/metadata/css/css-fonts/variations/font-shorthand.html.ini
deleted file mode 100644
index 30c11241f69..00000000000
--- a/tests/wpt/metadata/css/css-fonts/variations/font-shorthand.html.ini
+++ /dev/null
@@ -1,46 +0,0 @@
-[font-shorthand.html]
-  [Font shorthand: Font weight specified as number]
-    expected: FAIL
-
-  [Font shorthand: Font weight specified as calc()]
-    expected: FAIL
-
-  [Font shorthand: Font weight specified as calc(), value smaller than 1]
-    expected: FAIL
-
-  [Font shorthand: Font weight specified as calc(), value greater than 1000]
-    expected: FAIL
-
-  [Font shorthand: 'oblique' with positive angle]
-    expected: FAIL
-
-  [Font shorthand: 'oblique' with negative angle]
-    expected: FAIL
-
-  [Font shorthand: 'oblique' followed by valid small weight]
-    expected: FAIL
-
-  [Font shorthand: 'oblique' with positive angle followed by valid weight]
-    expected: FAIL
-
-  [Font shorthand: 'oblique' with negative angle followed by valid weight]
-    expected: FAIL
-
-  [Font shorthand: 'oblique' followed by valid calc() weight]
-    expected: FAIL
-
-  [Font shorthand: 'oblique' with angle followed by valid calc() weight]
-    expected: FAIL
-
-  [Font shorthand: 'oblique' followed by a to-be-clamped calc() weight]
-    expected: FAIL
-
-  [Font shorthand: calc() weight folowed by 'oblique']
-    expected: FAIL
-
-  [Font shorthand: calc() weight folowed by 'oblique' and slant angle]
-    expected: FAIL
-
-  [Font shorthand: To-be-clamped calc() weight folowed by 'oblique' and slant angle]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-fonts/variations/font-stretch.html.ini b/tests/wpt/metadata/css/css-fonts/variations/font-stretch.html.ini
index 934fe5409e8..3412ec0c36c 100644
--- a/tests/wpt/metadata/css/css-fonts/variations/font-stretch.html.ini
+++ b/tests/wpt/metadata/css/css-fonts/variations/font-stretch.html.ini
@@ -1,97 +1,5 @@
 [font-stretch.html]
-  [@supports: 0% - zero is legal]
-    expected: FAIL
-
-  [@getComputedStyle: 0% - zero is legal]
-    expected: FAIL
-
-  [@supports: 1% - legal percentage]
-    expected: FAIL
-
-  [@getComputedStyle: 1% - legal percentage]
-    expected: FAIL
-
-  [@supports: 10% - legal percentage]
-    expected: FAIL
-
-  [@getComputedStyle: 10% - legal percentage]
-    expected: FAIL
-
-  [@supports: 100% - legal percentage]
-    expected: FAIL
-
-  [@getComputedStyle: 100% - legal percentage]
-    expected: FAIL
-
-  [@supports: 1000% - legal percentage]
-    expected: FAIL
-
-  [@getComputedStyle: 1000% - legal percentage]
-    expected: FAIL
-
-  [@supports: 1e9% - huge legal percentage]
-    expected: FAIL
 
   [@getComputedStyle: 1e9% - huge legal percentage]
     expected: FAIL
 
-  [@getComputedStyle: ultra-condensed - legal enum]
-    expected: FAIL
-
-  [@getComputedStyle: extra-condensed - legal enum]
-    expected: FAIL
-
-  [@getComputedStyle: condensed - legal enum]
-    expected: FAIL
-
-  [@getComputedStyle: semi-condensed - legal enum]
-    expected: FAIL
-
-  [@getComputedStyle: normal - legal enum]
-    expected: FAIL
-
-  [@getComputedStyle: semi-expanded - legal enum]
-    expected: FAIL
-
-  [@getComputedStyle: expanded - legal enum]
-    expected: FAIL
-
-  [@getComputedStyle: extra-expanded - legal enum]
-    expected: FAIL
-
-  [@getComputedStyle: ultra-expanded - legal enum]
-    expected: FAIL
-
-  [@supports: calc(200.5%) - Simple calc value]
-    expected: FAIL
-
-  [@getComputedStyle: calc(200.5%) - Simple calc value]
-    expected: FAIL
-
-  [@supports: calc(50%*2 - 20%) - Valid calc expression]
-    expected: FAIL
-
-  [@getComputedStyle: calc(50%*2 - 20%) - Valid calc expression]
-    expected: FAIL
-
-  [@supports: calc(-100%) - Negative calc value (to be clamped)]
-    expected: FAIL
-
-  [@getComputedStyle: calc(-100%) - Negative calc value (to be clamped)]
-    expected: FAIL
-
-  [@supports: calc(50% - 50%*2) - Negative calc expression (to be clamped)]
-    expected: FAIL
-
-  [@getComputedStyle: calc(50% - 50%*2) - Negative calc expression (to be clamped)]
-    expected: FAIL
-
-  [Test font-stretch for overridden number condensed]
-    expected: FAIL
-
-  [Test font-stretch for overridden enum name resolved to number condensed]
-    expected: FAIL
-
-  [Test font-stretch for inherited named enum resolved to number condensed]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-fonts/variations/font-style-interpolation.html.ini b/tests/wpt/metadata/css/css-fonts/variations/font-style-interpolation.html.ini
index e37fe238ce4..fd9f8617078 100644
--- a/tests/wpt/metadata/css/css-fonts/variations/font-style-interpolation.html.ini
+++ b/tests/wpt/metadata/css/css-fonts/variations/font-style-interpolation.html.ini
@@ -3,6 +3,3 @@
   [font-style animation]
     expected: TIMEOUT
 
-  [font-style transition]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-fonts/variations/font-style-parsing.html.ini b/tests/wpt/metadata/css/css-fonts/variations/font-style-parsing.html.ini
deleted file mode 100644
index 6653e80949f..00000000000
--- a/tests/wpt/metadata/css/css-fonts/variations/font-style-parsing.html.ini
+++ /dev/null
@@ -1,43 +0,0 @@
-[font-style-parsing.html]
-  [Font-style: 'oblique' followed by zero degrees is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by positive angle in degrees is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by positive angle in radians is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by positive angle in gradians is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by positive angle in turns is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by negative angle is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by fractional angle is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by maxumum 90 degree angle is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by minimum -90 degree angle is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by positive angle is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by calc is valid]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by calc is valid even if it must be clamped (no computation)]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by calc is valid even if it must be clamped (with computation)]
-    expected: FAIL
-
-  [Font-style: 'oblique' followed by calc is valid even if it mixes units (with computation)]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-fonts/variations/font-weight-lighter-bolder.html.ini b/tests/wpt/metadata/css/css-fonts/variations/font-weight-lighter-bolder.html.ini
deleted file mode 100644
index 1ef0aa9b30c..00000000000
--- a/tests/wpt/metadata/css/css-fonts/variations/font-weight-lighter-bolder.html.ini
+++ /dev/null
@@ -1,40 +0,0 @@
-[font-weight-lighter-bolder.html]
-  [Test lighter font-weight for base weight 99]
-    expected: FAIL
-
-  [Test bolder font-weight for base weight 99]
-    expected: FAIL
-
-  [Test bolder font-weight for base weight 349]
-    expected: FAIL
-
-  [Test lighter font-weight for base weight 550]
-    expected: FAIL
-
-  [Test bolder font-weight for base weight 550]
-    expected: FAIL
-
-  [Test lighter font-weight for base weight 749]
-    expected: FAIL
-
-  [Test bolder font-weight for base weight 749]
-    expected: FAIL
-
-  [Test lighter font-weight for base weight 750]
-    expected: FAIL
-
-  [Test bolder font-weight for base weight 750]
-    expected: FAIL
-
-  [Test lighter font-weight for base weight 899]
-    expected: FAIL
-
-  [Test bolder font-weight for base weight 899]
-    expected: FAIL
-
-  [Test lighter font-weight for base weight 901]
-    expected: FAIL
-
-  [Test bolder font-weight for base weight 901]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-fonts/variations/font-weight-parsing.html.ini b/tests/wpt/metadata/css/css-fonts/variations/font-weight-parsing.html.ini
deleted file mode 100644
index 05e9036381d..00000000000
--- a/tests/wpt/metadata/css/css-fonts/variations/font-weight-parsing.html.ini
+++ /dev/null
@@ -1,55 +0,0 @@
-[font-weight-parsing.html]
-  [@supports: Values that are not multiple of 100 should be parsed successfully]
-    expected: FAIL
-
-  [@supports: Non-integer Values should be parsed successfully]
-    expected: FAIL
-
-  [@supports: Minimum allowed value should be parsed successfully]
-    expected: FAIL
-
-  [@supports: Maximum allowed value should be parsed successfully]
-    expected: FAIL
-
-  [@supports: Simple calc value]
-    expected: FAIL
-
-  [@supports: Negative simple calc value (to be clamped)]
-    expected: FAIL
-
-  [@supports: Out-of-range simple calc value (to be clamped)]
-    expected: FAIL
-
-  [@supports: Valid calc expression]
-    expected: FAIL
-
-  [@supports: Valid calc expression with out-of-range value (to be clamped)]
-    expected: FAIL
-
-  [Computed style: Values that are not multiple of 100 should be parsed successfully]
-    expected: FAIL
-
-  [Computed style: Non-integer Values should be parsed successfully]
-    expected: FAIL
-
-  [Computed style: Minimum allowed value should be parsed successfully]
-    expected: FAIL
-
-  [Computed style: Maximum allowed value should be parsed successfully]
-    expected: FAIL
-
-  [Computed style: Simple calc value]
-    expected: FAIL
-
-  [Computed style: Negative simple calc value (to be clamped)]
-    expected: FAIL
-
-  [Computed style: Out-of-range simple calc value (to be clamped)]
-    expected: FAIL
-
-  [Computed style: Valid calc expression]
-    expected: FAIL
-
-  [Computed style: Valid calc expression with out-of-range value (to be clamped)]
-    expected: FAIL
-
diff --git a/tests/wpt/metadata/css/css-variables/variable-presentation-attribute.html.ini b/tests/wpt/metadata/css/css-variables/variable-presentation-attribute.html.ini
index da00995e02b..bbb64382d67 100644
--- a/tests/wpt/metadata/css/css-variables/variable-presentation-attribute.html.ini
+++ b/tests/wpt/metadata/css/css-variables/variable-presentation-attribute.html.ini
@@ -50,6 +50,9 @@
   [Testing 'font-size-adjust'.]
     expected: FAIL
 
+  [Testing 'font-stretch'.]
+    expected: FAIL
+
   [Testing 'glyph-orientation-horizontal'.]
     expected: FAIL