diff --git a/components/style/stylesheet_set.rs b/components/style/stylesheet_set.rs
index 0277842262e..eeb75e738e6 100644
--- a/components/style/stylesheet_set.rs
+++ b/components/style/stylesheet_set.rs
@@ -124,16 +124,6 @@ impl Default for DataValidity {
     }
 }
 
-/// Whether author styles are enabled.
-///
-/// This is used to support Gecko.
-#[allow(missing_docs)]
-#[derive(Clone, Copy, Debug, PartialEq, Eq)]
-pub enum AuthorStylesEnabled {
-    Yes,
-    No,
-}
-
 /// A struct to iterate over the different stylesheets to be flushed.
 pub struct StylesheetFlusher<'a, S>
 where
@@ -142,7 +132,6 @@ where
     origins_dirty: OriginSet,
     collections: &'a mut PerOrigin<SheetCollection<S>>,
     origin_data_validity: PerOrigin<DataValidity>,
-    author_styles_enabled: AuthorStylesEnabled,
     had_invalidations: bool,
 }
 
@@ -209,14 +198,6 @@ where
             "origin_data_validity should be a subset of origins_dirty!"
         );
 
-        if self.author_styles_enabled == AuthorStylesEnabled::No &&
-            origin == Origin::Author
-        {
-            return PerOriginFlusher {
-                iter: [].iter_mut(),
-                validity,
-            }
-        }
         PerOriginFlusher {
             iter: self.collections.borrow_mut_for_origin(&origin).entries.iter_mut(),
             validity,
@@ -411,9 +392,6 @@ where
 
     /// The invalidations for stylesheets added or removed from this document.
     invalidations: StylesheetInvalidationSet,
-
-    /// Whether author styles are enabled.
-    author_styles_enabled: AuthorStylesEnabled,
 }
 
 impl<S> DocumentStylesheetSet<S>
@@ -425,7 +403,6 @@ where
         Self {
             collections: Default::default(),
             invalidations: StylesheetInvalidationSet::new(),
-            author_styles_enabled: AuthorStylesEnabled::Yes,
         }
     }
 
@@ -510,18 +487,6 @@ where
         self.collections.borrow_mut_for_origin(&origin).remove(&sheet)
     }
 
-    /// Notes that the author style has been disabled for this document.
-    pub fn set_author_styles_enabled(&mut self, enabled: AuthorStylesEnabled) {
-        debug!("DocumentStylesheetSet::set_author_styles_enabled");
-        if self.author_styles_enabled == enabled {
-            return;
-        }
-        self.author_styles_enabled = enabled;
-        self.invalidations.invalidate_fully();
-        self.collections.borrow_mut_for_origin(&Origin::Author)
-            .set_data_validity_at_least(DataValidity::FullyInvalid)
-    }
-
     /// Returns whether the given set has changed from the last flush.
     pub fn has_changed(&self) -> bool {
         self.collections.iter_origins().any(|(collection, _)| collection.dirty)
@@ -560,7 +525,6 @@ where
 
         StylesheetFlusher {
             collections: &mut self.collections,
-            author_styles_enabled: self.author_styles_enabled,
             had_invalidations,
             origins_dirty,
             origin_data_validity,
diff --git a/components/style/stylist.rs b/components/style/stylist.rs
index 160c70df673..f656f77476b 100644
--- a/components/style/stylist.rs
+++ b/components/style/stylist.rs
@@ -41,7 +41,7 @@ use smallvec::SmallVec;
 use std::ops;
 use std::sync::Mutex;
 use style_traits::viewport::ViewportConstraints;
-use stylesheet_set::{AuthorStylesEnabled, DataValidity, SheetRebuildKind, DocumentStylesheetSet, StylesheetFlusher};
+use stylesheet_set::{DataValidity, SheetRebuildKind, DocumentStylesheetSet, StylesheetFlusher};
 #[cfg(feature = "gecko")]
 use stylesheets::{CounterStyleRule, FontFaceRule, FontFeatureValuesRule, PageRule};
 use stylesheets::{CssRule, Origin, OriginSet, PerOrigin, PerOriginIter};
@@ -332,6 +332,16 @@ impl DocumentCascadeData {
     }
 }
 
+/// Whether author styles are enabled.
+///
+/// This is used to support Gecko.
+#[allow(missing_docs)]
+#[derive(Clone, Copy, Debug, Eq, MallocSizeOf, PartialEq)]
+pub enum AuthorStylesEnabled {
+    Yes,
+    No,
+}
+
 /// A wrapper over a DocumentStylesheetSet that can be `Sync`, since it's only
 /// used and exposed via mutable methods in the `Stylist`.
 #[cfg_attr(feature = "servo", derive(MallocSizeOf))]
@@ -397,6 +407,9 @@ pub struct Stylist {
     /// cascade level.
     cascade_data: DocumentCascadeData,
 
+    /// Whether author styles are enabled.
+    author_styles_enabled: AuthorStylesEnabled,
+
     /// The rule tree, that stores the results of selector matching.
     rule_tree: RuleTree,
 
@@ -437,6 +450,7 @@ impl Stylist {
             quirks_mode,
             stylesheets: StylistStylesheetSet::new(),
             cascade_data: Default::default(),
+            author_styles_enabled: AuthorStylesEnabled::Yes,
             rule_tree: RuleTree::new(),
             num_rebuilds: 0,
         }
@@ -593,7 +607,7 @@ impl Stylist {
 
     /// Sets whether author style is enabled or not.
     pub fn set_author_styles_enabled(&mut self, enabled: AuthorStylesEnabled) {
-        self.stylesheets.set_author_styles_enabled(enabled);
+        self.author_styles_enabled = enabled;
     }
 
     /// Returns whether we've recorded any stylesheet change so far.
@@ -1221,8 +1235,11 @@ impl Stylist {
 
         let only_default_rules =
             rule_inclusion == RuleInclusion::DefaultOnly;
-        let matches_user_and_author_rules =
+        let matches_user_rules =
             rule_hash_target.matches_user_and_author_rules();
+        let matches_author_rules =
+            matches_user_rules &&
+            self.author_styles_enabled == AuthorStylesEnabled::Yes;
 
         // Step 1: Normal user-agent rules.
         if let Some(map) = self.cascade_data.user_agent.cascade_data.normal_rules(pseudo_element) {
@@ -1260,7 +1277,7 @@ impl Stylist {
         //      rule_hash_target.matches_user_and_author_rules())
         //
         // Which may be more what you would probably expect.
-        if matches_user_and_author_rules {
+        if matches_user_rules {
             // Step 3a: User normal rules.
             if let Some(map) = self.cascade_data.user.normal_rules(pseudo_element) {
                 map.get_all_matching_rules(
@@ -1280,7 +1297,7 @@ impl Stylist {
         // particular, normally document rules override ::slotted() rules, but
         // for !important it should be the other way around. So probably we need
         // to add some sort of AuthorScoped cascade level or something.
-        if !only_default_rules {
+        if matches_author_rules && !only_default_rules {
             // Match slotted rules in reverse order, so that the outer slotted
             // rules come before the inner rules (and thus have less priority).
             let mut slots = SmallVec::<[_; 3]>::new();
@@ -1308,9 +1325,9 @@ impl Stylist {
 
         // FIXME(emilio): It looks very wrong to match XBL / Shadow DOM rules
         // even for getDefaultComputedStyle!
+        //
+        // Also, this doesn't account for the author_styles_enabled stuff.
         let cut_off_inheritance = element.each_xbl_stylist(|stylist| {
-            // ServoStyleSet::CreateXBLServoStyleSet() loads XBL style sheets
-            // under eAuthorSheetFeatures level.
             if let Some(map) = stylist.cascade_data.author.normal_rules(pseudo_element) {
                 // NOTE(emilio): This is needed because the XBL stylist may
                 // think it has a different quirks mode than the document.
@@ -1337,9 +1354,7 @@ impl Stylist {
             }
         });
 
-        if matches_user_and_author_rules && !only_default_rules &&
-            !cut_off_inheritance
-        {
+        if matches_author_rules && !only_default_rules && !cut_off_inheritance {
             // Step 3c: Author normal rules.
             if let Some(map) = self.cascade_data.author.normal_rules(pseudo_element) {
                 map.get_all_matching_rules(
diff --git a/ports/geckolib/glue.rs b/ports/geckolib/glue.rs
index 94a46e3395f..fe46a215188 100644
--- a/ports/geckolib/glue.rs
+++ b/ports/geckolib/glue.rs
@@ -135,7 +135,6 @@ use style::selector_parser::{PseudoElementCascadeType, SelectorImpl};
 use style::shared_lock::{SharedRwLockReadGuard, StylesheetGuards, ToCssWithGuard, Locked};
 use style::string_cache::{Atom, WeakAtom};
 use style::style_adjuster::StyleAdjuster;
-use style::stylesheet_set::AuthorStylesEnabled;
 use style::stylesheets::{CssRule, CssRules, CssRuleType, CssRulesHelpers, DocumentRule};
 use style::stylesheets::{FontFeatureValuesRule, ImportRule, KeyframesRule, MediaRule};
 use style::stylesheets::{NamespaceRule, Origin, OriginSet, PageRule, StyleRule};
@@ -143,7 +142,7 @@ use style::stylesheets::{StylesheetContents, SupportsRule};
 use style::stylesheets::StylesheetLoader as StyleStylesheetLoader;
 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, RuleInclusion, Stylist};
+use style::stylist::{add_size_of_ua_cache, AuthorStylesEnabled, RuleInclusion, Stylist};
 use style::thread_state;
 use style::timer::Timer;
 use style::traversal::DomTraversal;
@@ -1248,11 +1247,18 @@ pub unsafe extern "C" fn Servo_StyleSet_FlushStyleSheets(
 #[no_mangle]
 pub extern "C" fn Servo_StyleSet_NoteStyleSheetsChanged(
     raw_data: RawServoStyleSetBorrowed,
-    author_style_disabled: bool,
     changed_origins: OriginFlags,
 ) {
     let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     data.stylist.force_stylesheet_origins_dirty(OriginSet::from(changed_origins));
+}
+
+#[no_mangle]
+pub extern "C" fn Servo_StyleSet_SetAuthorStyleDisabled(
+    raw_data: RawServoStyleSetBorrowed,
+    author_style_disabled: bool,
+) {
+    let mut data = PerDocumentStyleData::from_ffi(raw_data).borrow_mut();
     let enabled =
         if author_style_disabled {
             AuthorStylesEnabled::No