diff --git a/components/style/properties/declaration_block.rs b/components/style/properties/declaration_block.rs
index fe52e6059c7..7bae033c9d4 100644
--- a/components/style/properties/declaration_block.rs
+++ b/components/style/properties/declaration_block.rs
@@ -1263,11 +1263,12 @@ pub fn parse_style_attribute(
     url_data: &UrlExtraData,
     error_reporter: Option<&dyn ParseErrorReporter>,
     quirks_mode: QuirksMode,
+    rule_type: CssRuleType,
 ) -> PropertyDeclarationBlock {
     let context = ParserContext::new(
         Origin::Author,
         url_data,
-        Some(CssRuleType::Style),
+        Some(rule_type),
         ParsingMode::DEFAULT,
         quirks_mode,
         error_reporter,
@@ -1291,11 +1292,12 @@ pub fn parse_one_declaration_into(
     error_reporter: Option<&dyn ParseErrorReporter>,
     parsing_mode: ParsingMode,
     quirks_mode: QuirksMode,
+    rule_type: CssRuleType,
 ) -> Result<(), ()> {
     let context = ParserContext::new(
         Origin::Author,
         url_data,
-        Some(CssRuleType::Style),
+        Some(rule_type),
         parsing_mode,
         quirks_mode,
         error_reporter,
diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index 9f204a3c36d..f98df39a629 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -542,10 +542,12 @@ impl NonCustomPropertyId {
         false
     }
 
-    fn allowed_in(self, context: &ParserContext) -> bool {
+    /// Returns whether a given rule allows a given property.
+    #[inline]
+    pub fn allowed_in_rule(self, rule_type: CssRuleType) -> bool {
         debug_assert!(
             matches!(
-                context.rule_type(),
+                rule_type,
                 CssRuleType::Keyframe | CssRuleType::Page | CssRuleType::Style
             ),
             "Declarations are only expected inside a keyframe, page, or style rule."
@@ -559,14 +561,16 @@ impl NonCustomPropertyId {
             "DISALLOWED_IN_PAGE_RULE",
             lambda p: not p.allowed_in_page_rule
         )}
-        match context.rule_type() {
-            CssRuleType::Keyframe if DISALLOWED_IN_KEYFRAME_BLOCK.contains(self) => {
-                return false;
-            }
-            CssRuleType::Page if DISALLOWED_IN_PAGE_RULE.contains(self) => {
-                return false;
-            }
-            _ => {}
+        match rule_type {
+            CssRuleType::Keyframe => !DISALLOWED_IN_KEYFRAME_BLOCK.contains(self),
+            CssRuleType::Page => !DISALLOWED_IN_PAGE_RULE.contains(self),
+            _ => true
+        }
+    }
+
+    fn allowed_in(self, context: &ParserContext) -> bool {
+        if !self.allowed_in_rule(context.rule_type()) {
+            return false;
         }
 
         self.allowed_in_ignoring_rule_type(context)
diff --git a/components/style/stylesheets/mod.rs b/components/style/stylesheets/mod.rs
index f83595dacef..a5e71140742 100644
--- a/components/style/stylesheets/mod.rs
+++ b/components/style/stylesheets/mod.rs
@@ -299,7 +299,7 @@ impl CssRule {
 }
 
 #[allow(missing_docs)]
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[derive(Clone, Copy, Debug, Eq, FromPrimitive, PartialEq)]
 pub enum CssRuleType {
     // https://drafts.csswg.org/cssom/#the-cssrule-interface
     Style = 1,