diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index 69feaa2f1e5..5aabb5c5367 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -3302,9 +3302,13 @@ impl ComputedValues {
     pub fn computed_value_to_string(&self, property: PropertyDeclarationId) -> String {
         match property {
             PropertyDeclarationId::Longhand(id) => {
+                let context = resolved::Context {
+                    style: self,
+                };
                 let mut s = String::new();
-                self.get_resolved_value(
+                self.computed_or_resolved_value(
                     id,
+                    Some(&context),
                     &mut s
                 ).unwrap();
                 s
diff --git a/components/style/values/computed/text.rs b/components/style/values/computed/text.rs
index ba395c1c366..951626d536c 100644
--- a/components/style/values/computed/text.rs
+++ b/components/style/values/computed/text.rs
@@ -119,12 +119,20 @@ impl ToResolvedValue for LineHeight {
 
     fn to_resolved_value(self, context: &ResolvedContext) -> Self::ResolvedValue {
         // Resolve <number> to an absolute <length> based on font size.
-        if matches!(self, Self::Normal | Self::MozBlockHeight) {
-            return self;
+        #[cfg(feature = "gecko")] {
+            if matches!(self, Self::Normal | Self::MozBlockHeight) {
+                return self;
+            }
+            let wm = context.style.writing_mode;
+            let vertical = wm.is_vertical() && !wm.is_sideways();
+            return Self::Length(context.device.calc_line_height(&self, vertical, context.style.get_font(), Some(context.element_info.element)));
+        }
+        if let LineHeight::Number(num) = &self {
+            let size = context.style.get_font().clone_font_size().computed_size();
+            LineHeight::Length(NonNegativeLength::new(size.px() * num.0))
+        } else {
+            self
         }
-        let wm = context.style.writing_mode;
-        let vertical = wm.is_vertical() && !wm.is_sideways();
-        Self::Length(context.device.calc_line_height(&self, vertical, context.style.get_font(), Some(context.element_info.element)))
     }
 
     #[inline]
diff --git a/components/style/values/resolved/mod.rs b/components/style/values/resolved/mod.rs
index 4bd4be22d2a..49fb222d459 100644
--- a/components/style/values/resolved/mod.rs
+++ b/components/style/values/resolved/mod.rs
@@ -5,6 +5,7 @@
 //! Resolved values. These are almost always computed values, but in some cases
 //! there are used values.
 
+#[cfg(feature = "gecko")]
 use crate::media_queries::Device;
 use crate::properties::ComputedValues;
 use crate::ArcSlice;
@@ -18,9 +19,9 @@ mod counters;
 use crate::values::computed;
 
 /// Element-specific information needed to resolve property values.
+#[cfg(feature = "gecko")]
 pub struct ResolvedElementInfo<'a> {
     /// Element we're resolving line-height against.
-    #[cfg(feature = "gecko")]
     pub element: crate::gecko::wrapper::GeckoElement<'a>,
 }
 
@@ -30,8 +31,10 @@ pub struct Context<'a> {
     pub style: &'a ComputedValues,
     /// The device / document we're resolving style for. Useful to do font metrics stuff needed for
     /// line-height.
+    #[cfg(feature = "gecko")]
     pub device: &'a Device,
     /// The element-specific information to resolve the value.
+    #[cfg(feature = "gecko")]
     pub element_info: ResolvedElementInfo<'a>,
 }