diff --git a/layout/style/Loader.cpp b/layout/style/Loader.cpp
index f1a258240c69..843d1f7fe65d 100644
--- a/layout/style/Loader.cpp
+++ b/layout/style/Loader.cpp
@@ -1410,23 +1410,18 @@ Loader::InsertSheetInDoc(StyleSheet* aSheet,
 nsresult
 Loader::InsertChildSheet(StyleSheet* aSheet,
                          StyleSheet* aParentSheet,
-                         ImportRule* aGeckoParentRule,
-                         const RawServoStyleSheet* aServoChildSheet)
+                         ImportRule* aGeckoParentRule)
 {
   LOG(("css::Loader::InsertChildSheet"));
   MOZ_ASSERT(aSheet, "Nothing to insert");
   MOZ_ASSERT(aParentSheet, "Need a parent to insert into");
-  MOZ_ASSERT(!aSheet->IsGecko() || (aGeckoParentRule && !aServoChildSheet));
-  MOZ_ASSERT(!aSheet->IsServo() || (aServoChildSheet && !aGeckoParentRule));
+  MOZ_ASSERT(aSheet->IsGecko() == !!aGeckoParentRule);
+
   // child sheets should always start out enabled, even if they got
   // cloned off of top-level sheets which were disabled
   aSheet->SetEnabled(true);
-  if (aSheet->IsGecko()) {
+  if (aGeckoParentRule) {
     aGeckoParentRule->SetSheet(aSheet->AsGecko()); // This sets the ownerRule on the sheet
-  } else {
-    if (!aSheet->AsServo()->RawSheet()) {
-      aSheet->AsServo()->SetSheetForImport(aServoChildSheet);
-    }
   }
   aParentSheet->PrependStyleSheet(aSheet);
 
@@ -2204,15 +2199,12 @@ Loader::LoadChildSheet(StyleSheet* aParentSheet,
                        nsIURI* aURL,
                        dom::MediaList* aMedia,
                        ImportRule* aGeckoParentRule,
-                       const RawServoStyleSheet* aServoChildSheet,
                        LoaderReusableStyleSheets* aReusableSheets)
 {
   LOG(("css::Loader::LoadChildSheet"));
   NS_PRECONDITION(aURL, "Must have a URI to load");
   NS_PRECONDITION(aParentSheet, "Must have a parent sheet");
-
-  MOZ_ASSERT(!aParentSheet->IsGecko() || (aGeckoParentRule && !aServoChildSheet));
-  MOZ_ASSERT(!aParentSheet->IsServo() || (aServoChildSheet && !aGeckoParentRule));
+  MOZ_ASSERT(aParentSheet->IsGecko() == !!aGeckoParentRule);
 
   if (!mEnabled) {
     LOG_WARN(("  Not enabled"));
@@ -2225,11 +2217,7 @@ Loader::LoadChildSheet(StyleSheet* aParentSheet,
 
   // check for an associated document: if none, don't bother walking up the
   // parent sheets
-  //
-  // FIXME(emilio): Figure out whether this walk up is necessary (try seems
-  // green without it), and fix the parenting of stylesheets in the servo case
-  // if that's the case.
-  if (aParentSheet->GetAssociatedDocument() && aParentSheet->IsGecko()) {
+  if (aParentSheet->GetAssociatedDocument()) {
     StyleSheet* topSheet = aParentSheet;
     while (StyleSheet* parent = topSheet->GetParentSheet()) {
       topSheet = parent;
@@ -2294,8 +2282,7 @@ Loader::LoadChildSheet(StyleSheet* aParentSheet,
     PrepareSheet(sheet, empty, empty, aMedia, nullptr, isAlternate);
   }
 
-  rv = InsertChildSheet(sheet, aParentSheet, aGeckoParentRule,
-                        aServoChildSheet);
+  rv = InsertChildSheet(sheet, aParentSheet, aGeckoParentRule);
   NS_ENSURE_SUCCESS(rv, rv);
 
   if (state == eSheetComplete) {
diff --git a/layout/style/Loader.h b/layout/style/Loader.h
index d6cee7eb2a45..5a00852cda1f 100644
--- a/layout/style/Loader.h
+++ b/layout/style/Loader.h
@@ -292,8 +292,6 @@ public:
    * @param aGeckoParentRule the @import rule importing this child, when using
    *                         Gecko's style system. This is used to properly
    *                         order the child sheet list of aParentSheet.
-   * @param aServoChildSheet the child stylesheet of the @import rule, when
-   *                         using Servo's style system.
    * @param aSavedSheets any saved style sheets which could be reused
    *              for this load
    */
@@ -301,7 +299,6 @@ public:
                           nsIURI* aURL,
                           dom::MediaList* aMedia,
                           ImportRule* aGeckoParentRule,
-                          const RawServoStyleSheet* aServoChildSheet,
                           LoaderReusableStyleSheets* aSavedSheets);
 
   /**
@@ -519,8 +516,7 @@ private:
 
   nsresult InsertChildSheet(StyleSheet* aSheet,
                             StyleSheet* aParentSheet,
-                            ImportRule* aGeckoParentRule,
-                            const RawServoStyleSheet* aServoChildSheet);
+                            ImportRule* aGeckoParentRule);
 
   nsresult InternalLoadNonDocumentSheet(nsIURI* aURL,
                                         bool aIsPreload,
diff --git a/layout/style/ServoArcTypeList.h b/layout/style/ServoArcTypeList.h
index 41f49d6e2161..6fa2040618f4 100644
--- a/layout/style/ServoArcTypeList.h
+++ b/layout/style/ServoArcTypeList.h
@@ -7,7 +7,7 @@
 /* a list of all Servo Arc types used in stylo bindings for preprocessing */
 
 SERVO_ARC_TYPE(CssRules, ServoCssRules)
-SERVO_ARC_TYPE(StyleSheet, RawServoStyleSheet)
+SERVO_ARC_TYPE(StyleSheetContents, RawServoStyleSheetContents)
 SERVO_ARC_TYPE(ComputedValues, ServoComputedValues)
 SERVO_ARC_TYPE(DeclarationBlock, RawServoDeclarationBlock)
 SERVO_ARC_TYPE(StyleRule, RawServoStyleRule)
diff --git a/layout/style/ServoBindingList.h b/layout/style/ServoBindingList.h
index 7488367f1821..1cecd25314ee 100644
--- a/layout/style/ServoBindingList.h
+++ b/layout/style/ServoBindingList.h
@@ -22,20 +22,19 @@
 SERVO_BINDING_FUNC(Servo_Element_ClearData, void, RawGeckoElementBorrowed node)
 
 // Styleset and Stylesheet management
-SERVO_BINDING_FUNC(Servo_StyleSheet_Empty, RawServoStyleSheetStrong,
-                   mozilla::css::SheetParsingMode parsing_mode)
-SERVO_BINDING_FUNC(Servo_StyleSheet_FromUTF8Bytes, RawServoStyleSheetStrong,
+SERVO_BINDING_FUNC(Servo_StyleSheet_FromUTF8Bytes, RawServoStyleSheetContentsStrong,
                    mozilla::css::Loader* loader,
                    mozilla::ServoStyleSheet* gecko_stylesheet,
                    const nsACString* data,
                    mozilla::css::SheetParsingMode parsing_mode,
-                   const RawServoMediaList* media_list,
                    RawGeckoURLExtraData* extra_data,
                    uint32_t line_number_offset,
                    nsCompatibility quirks_mode)
+SERVO_BINDING_FUNC(Servo_StyleSheet_Empty, RawServoStyleSheetContentsStrong,
+                   mozilla::css::SheetParsingMode parsing_mode)
 SERVO_BINDING_FUNC(Servo_StyleSheet_ClearAndUpdate,
                    void,
-                   RawServoStyleSheetBorrowed stylesheet,
+                   RawServoStyleSheetContentsBorrowed stylesheet,
                    mozilla::css::Loader* loader,
                    mozilla::ServoStyleSheet* gecko_stylesheet,
                    const nsACString* data,
@@ -43,13 +42,14 @@ SERVO_BINDING_FUNC(Servo_StyleSheet_ClearAndUpdate,
                    uint32_t line_number_offset,
                    mozilla::css::LoaderReusableStyleSheets* reusable_sheets)
 SERVO_BINDING_FUNC(Servo_StyleSheet_HasRules, bool,
-                   RawServoStyleSheetBorrowed sheet)
+                   RawServoStyleSheetContentsBorrowed sheet)
 SERVO_BINDING_FUNC(Servo_StyleSheet_GetRules, ServoCssRulesStrong,
-                   RawServoStyleSheetBorrowed sheet)
-SERVO_BINDING_FUNC(Servo_StyleSheet_Clone, RawServoStyleSheetStrong,
-                   RawServoStyleSheetBorrowed sheet)
+                   RawServoStyleSheetContentsBorrowed sheet)
+SERVO_BINDING_FUNC(Servo_StyleSheet_Clone, RawServoStyleSheetContentsStrong,
+                   RawServoStyleSheetContentsBorrowed sheet)
 SERVO_BINDING_FUNC(Servo_StyleSheet_SizeOfIncludingThis, size_t,
-                   mozilla::MallocSizeOf malloc_size_of, RawServoStyleSheetBorrowed sheet)
+                   mozilla::MallocSizeOf malloc_size_of,
+                   RawServoStyleSheetContentsBorrowed sheet)
 SERVO_BINDING_FUNC(Servo_StyleSet_Init, RawServoStyleSetOwned, RawGeckoPresContextOwned pres_context)
 SERVO_BINDING_FUNC(Servo_StyleSet_Clear, void,
                    RawServoStyleSetBorrowed set)
@@ -62,24 +62,17 @@ SERVO_BINDING_FUNC(Servo_StyleSet_CompatModeChanged, void,
                    RawServoStyleSetBorrowed raw_data)
 SERVO_BINDING_FUNC(Servo_StyleSet_AppendStyleSheet, void,
                    RawServoStyleSetBorrowed set,
-                   RawServoStyleSheetBorrowed sheet,
-                   uint64_t unique_id)
+                   const mozilla::ServoStyleSheet* gecko_sheet)
 SERVO_BINDING_FUNC(Servo_StyleSet_PrependStyleSheet, void,
                    RawServoStyleSetBorrowed set,
-                   RawServoStyleSheetBorrowed sheet,
-                   uint64_t unique_id)
+                   const mozilla::ServoStyleSheet* gecko_sheet)
 SERVO_BINDING_FUNC(Servo_StyleSet_RemoveStyleSheet, void,
                    RawServoStyleSetBorrowed set,
-                   uint64_t unique_id)
+                   const mozilla::ServoStyleSheet* gecko_sheet)
 SERVO_BINDING_FUNC(Servo_StyleSet_InsertStyleSheetBefore, void,
                    RawServoStyleSetBorrowed set,
-                   RawServoStyleSheetBorrowed sheet,
-                   uint64_t unique_id,
-                   uint64_t before_unique_id)
-SERVO_BINDING_FUNC(Servo_StyleSet_UpdateStyleSheet, void,
-                   RawServoStyleSetBorrowed set,
-                   RawServoStyleSheetBorrowed sheet,
-                   uint64_t unique_id)
+                   const mozilla::ServoStyleSheet* gecko_sheet,
+                   const mozilla::ServoStyleSheet* before)
 SERVO_BINDING_FUNC(Servo_StyleSet_FlushStyleSheets, void, RawServoStyleSetBorrowed set,
                    RawGeckoElementBorrowedOrNull doc_elem)
 SERVO_BINDING_FUNC(Servo_StyleSet_NoteStyleSheetsChanged, void,
@@ -115,8 +108,11 @@ SERVO_BINDING_FUNC(Servo_CssRules_ListTypes, void,
                    nsTArrayBorrowed_uintptr_t result)
 SERVO_BINDING_FUNC(Servo_CssRules_InsertRule, nsresult,
                    ServoCssRulesBorrowed rules,
-                   RawServoStyleSheetBorrowed sheet, const nsACString* rule,
-                   uint32_t index, bool nested, mozilla::css::Loader* loader,
+                   RawServoStyleSheetContentsBorrowed sheet,
+                   const nsACString* rule,
+                   uint32_t index,
+                   bool nested,
+                   mozilla::css::Loader* loader,
                    mozilla::ServoStyleSheet* gecko_stylesheet,
                    uint16_t* rule_type)
 SERVO_BINDING_FUNC(Servo_CssRules_DeleteRule, nsresult,
@@ -171,7 +167,8 @@ SERVO_BINDING_FUNC(Servo_StyleRule_GetSelectorCount, void,
                    RawServoStyleRuleBorrowed rule, uint32_t* count)
 SERVO_BINDING_FUNC(Servo_ImportRule_GetHref, void,
                    RawServoImportRuleBorrowed rule, nsAString* result)
-SERVO_BINDING_FUNC(Servo_ImportRule_GetSheet, const RawServoStyleSheet*,
+SERVO_BINDING_FUNC(Servo_ImportRule_GetSheet,
+                   const mozilla::ServoStyleSheet*,
                    RawServoImportRuleBorrowed rule)
 SERVO_BINDING_FUNC(Servo_Keyframe_GetKeyText, void,
                    RawServoKeyframeBorrowed keyframe, nsAString* result)
@@ -198,7 +195,8 @@ SERVO_BINDING_FUNC(Servo_KeyframesRule_FindRule, uint32_t,
 // Returns whether it successfully appends the rule.
 SERVO_BINDING_FUNC(Servo_KeyframesRule_AppendRule, bool,
                    RawServoKeyframesRuleBorrowed rule,
-                   RawServoStyleSheetBorrowed sheet, const nsACString* css)
+                   RawServoStyleSheetContentsBorrowed sheet,
+                   const nsACString* css)
 SERVO_BINDING_FUNC(Servo_KeyframesRule_DeleteRule, void,
                    RawServoKeyframesRuleBorrowed rule, uint32_t index)
 SERVO_BINDING_FUNC(Servo_MediaRule_GetMedia, RawServoMediaListStrong,
diff --git a/layout/style/ServoBindings.cpp b/layout/style/ServoBindings.cpp
index 6246bbac8ef6..0a70ea9940a0 100644
--- a/layout/style/ServoBindings.cpp
+++ b/layout/style/ServoBindings.cpp
@@ -2341,7 +2341,6 @@ void
 Gecko_LoadStyleSheet(css::Loader* aLoader,
                      ServoStyleSheet* aParent,
                      css::LoaderReusableStyleSheets* aReusableSheets,
-                     RawServoStyleSheetBorrowed aChildSheet,
                      RawGeckoURLExtraData* aBaseURLData,
                      const uint8_t* aURLString,
                      uint32_t aURLStringLength,
@@ -2368,7 +2367,7 @@ Gecko_LoadStyleSheet(css::Loader* aLoader,
     return;
   }
 
-  aLoader->LoadChildSheet(aParent, uri, media, nullptr, aChildSheet, aReusableSheets);
+  aLoader->LoadChildSheet(aParent, uri, media, nullptr, aReusableSheets);
 }
 
 const nsMediaFeature*
diff --git a/layout/style/ServoBindings.h b/layout/style/ServoBindings.h
index 3ba8c3f14afd..91a01411b33b 100644
--- a/layout/style/ServoBindings.h
+++ b/layout/style/ServoBindings.h
@@ -146,7 +146,6 @@ RawGeckoNodeBorrowedOrNull Gecko_GetNextStyleChild(RawGeckoStyleChildrenIterator
 void Gecko_LoadStyleSheet(mozilla::css::Loader* loader,
                           mozilla::ServoStyleSheet* parent,
                           mozilla::css::LoaderReusableStyleSheets* reusable_sheets,
-                          RawServoStyleSheetBorrowed child_sheet,
                           RawGeckoURLExtraData* base_url_data,
                           const uint8_t* url_bytes,
                           uint32_t url_length,
diff --git a/layout/style/ServoBindings.toml b/layout/style/ServoBindings.toml
index 2f9754db9823..dc18d35d0782 100644
--- a/layout/style/ServoBindings.toml
+++ b/layout/style/ServoBindings.toml
@@ -61,6 +61,7 @@ headers = [
     "mozilla/dom/NameSpaceConstants.h",
     "mozilla/LookAndFeel.h",
     "mozilla/ServoBindings.h",
+    "mozilla/ServoMediaList.h",
     "nsCSSCounterStyleRule.h",
     "nsCSSFontFaceRule.h",
     "nsMediaFeatures.h",
@@ -118,8 +119,8 @@ whitelist-types = [
     "mozilla::ComputedTiming",
     "mozilla::ComputedTimingFunction",
     "mozilla::ComputedTimingFunction::BeforeFlag",
-    "mozilla::ServoStyleSheet",
     "mozilla::ServoElementSnapshot.*",
+    "mozilla::ServoStyleSheetInner",
     "mozilla::CSSPseudoClassType",
     "mozilla::css::SheetParsingMode",
     "mozilla::css::URLMatchingFunction",
@@ -258,6 +259,7 @@ whitelist-types = [
     "mozilla::binding_danger::AssertAndSuppressCleanupPolicy",
     "mozilla::ParsingMode",
     "mozilla::InheritTarget",
+    "mozilla::ServoMediaList",
     "mozilla::StyleRuleInclusion",
     "nsStyleTransformMatrix::MatrixTransformOperator",
 ]
@@ -345,6 +347,8 @@ structs-types = [
     "RawGeckoNode",
     "RawServoAnimationValue",
     "RawGeckoServoAnimationValueList",
+    "RawServoMediaList",
+    "RawServoStyleSheetContents",
     "RawServoDeclarationBlock",
     "RawServoStyleRule",
     "RawGeckoPresContext",
diff --git a/layout/style/ServoCSSRuleList.cpp b/layout/style/ServoCSSRuleList.cpp
index c11a82e13f7e..44bfc92775d1 100644
--- a/layout/style/ServoCSSRuleList.cpp
+++ b/layout/style/ServoCSSRuleList.cpp
@@ -30,31 +30,6 @@ ServoCSSRuleList::ServoCSSRuleList(already_AddRefed<ServoCssRules> aRawRules,
   , mRawRules(aRawRules)
 {
   Servo_CssRules_ListTypes(mRawRules, &mRules);
-  // Only top level rule list can have @import rules.
-  if (aDirectOwnerStyleSheet) {
-    nsDataHashtable<nsPtrHashKey<const RawServoStyleSheet>,
-                    ServoStyleSheet*> stylesheets;
-    aDirectOwnerStyleSheet->EnumerateChildSheets(
-      [&stylesheets](StyleSheet* child) {
-        ServoStyleSheet* servoSheet = child->AsServo();
-        const RawServoStyleSheet* rawSheet = servoSheet->RawSheet();
-        MOZ_ASSERT(!stylesheets.Get(rawSheet, nullptr),
-                   "Multiple child sheets with same raw sheet?");
-        stylesheets.Put(rawSheet, servoSheet);
-      });
-    for (auto i : IntegerRange(mRules.Length())) {
-      if (mRules[i] != nsIDOMCSSRule::IMPORT_RULE) {
-        // Only @charset can be put before @import rule, but @charset
-        // rules don't have corresponding object, so if a rule is not
-        // @import rule, there is definitely no @import rule after it.
-        break;
-      }
-      ConstructImportRule(i, [&stylesheets](const RawServoStyleSheet* raw) {
-        // Child sheet will not be constructed if the import rule has a bad URL.
-        return stylesheets.GetAndRemove(raw).valueOr(nullptr);
-      });
-    }
-  }
 }
 
 // QueryInterface implementation for ServoCSSRuleList
@@ -210,9 +185,8 @@ ServoCSSRuleList::DropReference()
   DropAllRules();
 }
 
-template<typename ChildSheetGetter>
 void
-ServoCSSRuleList::ConstructImportRule(uint32_t aIndex, ChildSheetGetter aGetter)
+ServoCSSRuleList::ConstructImportRule(uint32_t aIndex)
 {
   MOZ_ASSERT(mRules[aIndex] == nsIDOMCSSRule::IMPORT_RULE);
 
@@ -220,15 +194,9 @@ ServoCSSRuleList::ConstructImportRule(uint32_t aIndex, ChildSheetGetter aGetter)
   RefPtr<RawServoImportRule> rawRule =
     Servo_CssRules_GetImportRuleAt(mRawRules, aIndex,
                                    &line, &column).Consume();
-  const RawServoStyleSheet*
-    rawChildSheet = Servo_ImportRule_GetSheet(rawRule);
-  ServoStyleSheet* childSheet = aGetter(rawChildSheet);
-  // There is one case where we don't construct a child sheet for an import
-  // rule: when the URL doesn't resolve. In that cases we still want to create
-  // an import rule object, though we note it as an exceptional condition
-  // in debug builds.
-  NS_WARNING_ASSERTION(childSheet,
-                       "stylo: failed to get child sheet for @import rule");
+  auto* childSheet =
+    const_cast<ServoStyleSheet*>(Servo_ImportRule_GetSheet(rawRule));
+  MOZ_ASSERT(childSheet);
   RefPtr<ServoImportRule>
     ruleObj = new ServoImportRule(Move(rawRule), childSheet, line, column);
   if (childSheet) {
@@ -253,7 +221,7 @@ ServoCSSRuleList::InsertRule(const nsAString& aRule, uint32_t aIndex)
     loader = doc->CSSLoader();
   }
   uint16_t type;
-  nsresult rv = Servo_CssRules_InsertRule(mRawRules, mStyleSheet->RawSheet(),
+  nsresult rv = Servo_CssRules_InsertRule(mRawRules, mStyleSheet->RawContents(),
                                           &rule, aIndex, nested,
                                           loader, mStyleSheet, &type);
   if (NS_FAILED(rv)) {
@@ -262,40 +230,7 @@ ServoCSSRuleList::InsertRule(const nsAString& aRule, uint32_t aIndex)
   mRules.InsertElementAt(aIndex, type);
   if (type == nsIDOMCSSRule::IMPORT_RULE) {
     MOZ_ASSERT(!nested, "@import rule cannot be nested");
-    ConstructImportRule(aIndex, [this](const RawServoStyleSheet* raw) {
-      // Our goal is to find a ServoStyleSheet that is a child of mStyleSheet
-      // that has a RawSheet equal to raw. This will be true when the call
-      // to Gecko_LoadStyleSheet finished successfully. But that function
-      // might have failed. A malformed URL will cause an early exit
-      // where no ServoStyleSheet is created and added as a child
-      // to mStyleSheet. In that case, we return a null ServoStyleSheet.
-
-      // See if there are any child sheets.
-      StyleSheet* sheet = mStyleSheet->GetMostRecentlyAddedChildSheet();
-      if (sheet) {
-        ServoStyleSheet* firstChild = sheet->AsServo();
-
-        // See if this first child has a RawSheet of raw.
-        if (firstChild->RawSheet() == raw) {
-          // This is the one we expected to find, so return it.
-          return firstChild;
-        }
-#if DEBUG
-        // See if the child sheet was added in another position,
-        // which would be incorrect behavior.
-        mStyleSheet->EnumerateChildSheets([raw](StyleSheet* child) {
-          ServoStyleSheet* servoChild = child->AsServo();
-          MOZ_ASSERT(servoChild->RawSheet() != raw,
-            "New child sheet should either be first on the list or not present");
-        });
-#endif
-      }
-
-      // The raw sheet wasn't found in mStyleSheets child sheet list at all.
-      // This is probably a result of a bad URL in the import rule.
-      NS_WARNING("Import rule didn't create a ServoStyleSheet... bad URL?");
-      return static_cast<ServoStyleSheet*>(nullptr);
-    });
+    ConstructImportRule(aIndex);
   }
   return rv;
 }
diff --git a/layout/style/ServoCSSRuleList.h b/layout/style/ServoCSSRuleList.h
index d31474261ab7..52cf58fbbf69 100644
--- a/layout/style/ServoCSSRuleList.h
+++ b/layout/style/ServoCSSRuleList.h
@@ -71,9 +71,6 @@ private:
 
   void DropAllRules();
 
-  template<typename ChildSheetGetter>
-  inline void ConstructImportRule(uint32_t aIndex, ChildSheetGetter aGetter);
-
   // mStyleSheet may be nullptr when it drops the reference to us.
   ServoStyleSheet* mStyleSheet = nullptr;
   // mParentRule is nullptr if it isn't a nested rule list.
diff --git a/layout/style/ServoKeyframesRule.cpp b/layout/style/ServoKeyframesRule.cpp
index aeb4b9efde4c..058cde2196ed 100644
--- a/layout/style/ServoKeyframesRule.cpp
+++ b/layout/style/ServoKeyframesRule.cpp
@@ -75,6 +75,7 @@ public:
   void AppendRule() {
     mRules.AppendObject(nullptr);
   }
+
   void RemoveRule(uint32_t aIndex) {
     mRules.RemoveObjectAt(aIndex);
   }
@@ -279,11 +280,10 @@ ServoKeyframesRule::AppendRule(const nsAString& aRule)
 
   NS_ConvertUTF16toUTF8 rule(aRule);
   UpdateRule([this, sheet, &rule]() {
-    if (Servo_KeyframesRule_AppendRule(mRawRule, sheet->AsServo()->RawSheet(),
-                                       &rule)) {
-      if (mKeyframeList) {
-        mKeyframeList->AppendRule();
-      }
+    bool parsedOk = Servo_KeyframesRule_AppendRule(
+      mRawRule, sheet->AsServo()->RawContents(), &rule);
+    if (parsedOk && mKeyframeList) {
+      mKeyframeList->AppendRule();
     }
   });
   return NS_OK;
diff --git a/layout/style/ServoStyleSet.cpp b/layout/style/ServoStyleSet.cpp
index 87e8d66a73e9..0564b76566d0 100644
--- a/layout/style/ServoStyleSet.cpp
+++ b/layout/style/ServoStyleSet.cpp
@@ -34,15 +34,6 @@
 using namespace mozilla;
 using namespace mozilla::dom;
 
-static inline uint64_t UniqueIDForSheet(ServoStyleSheet* aSheet)
-{
-  // Servo tracks sheets by unique ID, and it's important that a given
-  // ServoStyleSheet has the same unique ID throughout its lifetime.
-  // Instead of tracking an arbitrary unique ID for each sheet,
-  // we use the sheet address as a unique ID.
-  return reinterpret_cast<uint64_t>(aSheet);
-}
-
 ServoStyleSet::ServoStyleSet()
   : mPresContext(nullptr)
   , mAllowResolveStaleStyles(false)
@@ -81,10 +72,9 @@ ServoStyleSet::Init(nsPresContext* aPresContext, nsBindingManager* aBindingManag
       // because Servo only needs to maintain relative ordering within a sheet
       // type, which this preserves.
 
-      MOZ_ASSERT(sheet->RawSheet(), "We should only append non-null raw sheets.");
-      Servo_StyleSet_AppendStyleSheet(mRawSet.get(),
-                                      sheet->RawSheet(),
-                                      UniqueIDForSheet(sheet));
+      MOZ_ASSERT(sheet->RawContents(),
+                 "We should only append non-null raw sheets.");
+      Servo_StyleSet_AppendStyleSheet(mRawSet.get(), sheet);
     }
   }
 
@@ -709,7 +699,7 @@ ServoStyleSet::AppendStyleSheet(SheetType aType,
   MOZ_ASSERT(aSheet);
   MOZ_ASSERT(aSheet->IsApplicable());
   MOZ_ASSERT(nsStyleSet::IsCSSSheetType(aType));
-  MOZ_ASSERT(aSheet->RawSheet(), "Raw sheet should be in place before insertion.");
+  MOZ_ASSERT(aSheet->RawContents(), "Raw sheet should be in place before insertion.");
 
   RemoveSheetOfType(aType, aSheet);
   AppendSheetOfType(aType, aSheet);
@@ -718,9 +708,7 @@ ServoStyleSet::AppendStyleSheet(SheetType aType,
     // Maintain a mirrored list of sheets on the servo side.
     // Servo will remove aSheet from its original position as part of the call
     // to Servo_StyleSet_AppendStyleSheet.
-    Servo_StyleSet_AppendStyleSheet(mRawSet.get(),
-                                    aSheet->RawSheet(),
-                                    UniqueIDForSheet(aSheet));
+    Servo_StyleSet_AppendStyleSheet(mRawSet.get(), aSheet);
     SetStylistStyleSheetsDirty();
   }
 
@@ -734,7 +722,8 @@ ServoStyleSet::PrependStyleSheet(SheetType aType,
   MOZ_ASSERT(aSheet);
   MOZ_ASSERT(aSheet->IsApplicable());
   MOZ_ASSERT(nsStyleSet::IsCSSSheetType(aType));
-  MOZ_ASSERT(aSheet->RawSheet(), "Raw sheet should be in place before insertion.");
+  MOZ_ASSERT(aSheet->RawContents(),
+             "Raw sheet should be in place before insertion.");
 
   RemoveSheetOfType(aType, aSheet);
   PrependSheetOfType(aType, aSheet);
@@ -743,9 +732,7 @@ ServoStyleSet::PrependStyleSheet(SheetType aType,
     // Maintain a mirrored list of sheets on the servo side.
     // Servo will remove aSheet from its original position as part of the call
     // to Servo_StyleSet_PrependStyleSheet.
-    Servo_StyleSet_PrependStyleSheet(mRawSet.get(),
-                                     aSheet->RawSheet(),
-                                     UniqueIDForSheet(aSheet));
+    Servo_StyleSet_PrependStyleSheet(mRawSet.get(), aSheet);
     SetStylistStyleSheetsDirty();
   }
 
@@ -762,7 +749,7 @@ ServoStyleSet::RemoveStyleSheet(SheetType aType,
   RemoveSheetOfType(aType, aSheet);
   if (mRawSet) {
     // Maintain a mirrored list of sheets on the servo side.
-    Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), UniqueIDForSheet(aSheet));
+    Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), aSheet);
     SetStylistStyleSheetsDirty();
   }
 
@@ -784,7 +771,7 @@ ServoStyleSet::ReplaceSheets(SheetType aType,
   for (const auto& sheet : mSheets[aType]) {
     sheet->DropStyleSet(this);
     if (mRawSet) {
-      Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), UniqueIDForSheet(sheet));
+      Servo_StyleSet_RemoveStyleSheet(mRawSet.get(), sheet);
     }
   }
   mSheets[aType].Clear();
@@ -793,10 +780,8 @@ ServoStyleSet::ReplaceSheets(SheetType aType,
   for (auto& sheet : aNewSheets) {
     AppendSheetOfType(aType, sheet);
     if (mRawSet) {
-      MOZ_ASSERT(sheet->RawSheet(), "Raw sheet should be in place before replacement.");
-      Servo_StyleSet_AppendStyleSheet(mRawSet.get(),
-                                      sheet->RawSheet(),
-                                      UniqueIDForSheet(sheet));
+      MOZ_ASSERT(sheet->RawContents(), "Raw sheet should be in place before replacement.");
+      Servo_StyleSet_AppendStyleSheet(mRawSet.get(), sheet);
     }
   }
 
@@ -812,8 +797,8 @@ ServoStyleSet::InsertStyleSheetBefore(SheetType aType,
   MOZ_ASSERT(aReferenceSheet);
   MOZ_ASSERT(aNewSheet->IsApplicable());
   MOZ_ASSERT(aNewSheet != aReferenceSheet, "Can't place sheet before itself.");
-  MOZ_ASSERT(aNewSheet->RawSheet(), "Raw sheet should be in place before insertion.");
-  MOZ_ASSERT(aReferenceSheet->RawSheet(), "Reference sheet should have a raw sheet.");
+  MOZ_ASSERT(aNewSheet->RawContents(), "Raw sheet should be in place before insertion.");
+  MOZ_ASSERT(aReferenceSheet->RawContents(), "Reference sheet should have a raw sheet.");
 
   // Servo will remove aNewSheet from its original position as part of the
   // call to Servo_StyleSet_InsertStyleSheetBefore.
@@ -822,10 +807,8 @@ ServoStyleSet::InsertStyleSheetBefore(SheetType aType,
 
   if (mRawSet) {
     // Maintain a mirrored list of sheets on the servo side.
-    Servo_StyleSet_InsertStyleSheetBefore(mRawSet.get(),
-                                          aNewSheet->RawSheet(),
-                                          UniqueIDForSheet(aNewSheet),
-                                          UniqueIDForSheet(aReferenceSheet));
+    Servo_StyleSet_InsertStyleSheetBefore(
+        mRawSet.get(), aNewSheet, aReferenceSheet);
     SetStylistStyleSheetsDirty();
   }
 
@@ -836,16 +819,7 @@ void
 ServoStyleSet::UpdateStyleSheet(ServoStyleSheet* aSheet)
 {
   MOZ_ASSERT(aSheet);
-
-  if (mRawSet) {
-    // Inform servo that the underlying raw sheet has changed.
-    Servo_StyleSet_UpdateStyleSheet(mRawSet.get(),
-                                    aSheet->RawSheet(),
-                                    UniqueIDForSheet(aSheet));
-    // No need to set the stylesheets as dirty, since this is only
-    // used to notify servo of a cloned raw sheet. It styles the
-    // same until the sheet is changed through other methods.
-  }
+  // TODO(emilio): Get rid of this.
 }
 
 int32_t
@@ -856,8 +830,7 @@ ServoStyleSet::SheetCount(SheetType aType) const
 }
 
 ServoStyleSheet*
-ServoStyleSet::StyleSheetAt(SheetType aType,
-                            int32_t aIndex) const
+ServoStyleSet::StyleSheetAt(SheetType aType, int32_t aIndex) const
 {
   MOZ_ASSERT(nsStyleSet::IsCSSSheetType(aType));
   return mSheets[aType][aIndex];
@@ -882,7 +855,7 @@ ServoStyleSet::AddDocStyleSheet(ServoStyleSheet* aSheet,
                                 nsIDocument* aDocument)
 {
   MOZ_ASSERT(aSheet->IsApplicable());
-  MOZ_ASSERT(aSheet->RawSheet(), "Raw sheet should be in place by this point.");
+  MOZ_ASSERT(aSheet->RawContents(), "Raw sheet should be in place by this point.");
 
   RefPtr<StyleSheet> strong(aSheet);
 
@@ -898,10 +871,7 @@ ServoStyleSet::AddDocStyleSheet(ServoStyleSheet* aSheet,
 
     if (mRawSet) {
       // Maintain a mirrored list of sheets on the servo side.
-      Servo_StyleSet_InsertStyleSheetBefore(mRawSet.get(),
-                                            aSheet->RawSheet(),
-                                            UniqueIDForSheet(aSheet),
-                                            UniqueIDForSheet(beforeSheet));
+      Servo_StyleSet_InsertStyleSheetBefore(mRawSet.get(), aSheet, beforeSheet);
       SetStylistStyleSheetsDirty();
     }
   } else {
@@ -910,9 +880,7 @@ ServoStyleSet::AddDocStyleSheet(ServoStyleSheet* aSheet,
 
     if (mRawSet) {
       // Maintain a mirrored list of sheets on the servo side.
-      Servo_StyleSet_AppendStyleSheet(mRawSet.get(),
-                                      aSheet->RawSheet(),
-                                      UniqueIDForSheet(aSheet));
+      Servo_StyleSet_AppendStyleSheet(mRawSet.get(), aSheet);
       SetStylistStyleSheetsDirty();
     }
   }
diff --git a/layout/style/ServoStyleSheet.cpp b/layout/style/ServoStyleSheet.cpp
index a19587e7cef7..ea75a074c521 100644
--- a/layout/style/ServoStyleSheet.cpp
+++ b/layout/style/ServoStyleSheet.cpp
@@ -44,8 +44,8 @@ ServoStyleSheetInner::ServoStyleSheetInner(ServoStyleSheetInner& aCopy,
 {
   MOZ_COUNT_CTOR(ServoStyleSheetInner);
 
-  // Actually clone aCopy's mSheet and use that as our mSheet.
-  mSheet = Servo_StyleSheet_Clone(aCopy.mSheet).Consume();
+  // Actually clone aCopy's mContents and use that as ours.
+  mContents = Servo_StyleSheet_Clone(aCopy.mContents).Consume();
 
   mURLData = aCopy.mURLData;
 }
@@ -68,10 +68,10 @@ size_t
 ServoStyleSheetInner::SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const
 {
   size_t n = aMallocSizeOf(this);
-  // mSheet will be null if the parsing has not completed.
-  if (mSheet) {
-    n += Servo_StyleSheet_SizeOfIncludingThis(ServoStyleSheetMallocSizeOf,
-                                              mSheet);
+  // mContents will be null if the parsing has not completed.
+  if (mContents) {
+    n += Servo_StyleSheet_SizeOfIncludingThis(
+        ServoStyleSheetMallocSizeOf, mContents);
   }
   return n;
 }
@@ -141,7 +141,7 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 bool
 ServoStyleSheet::HasRules() const
 {
-  return Inner()->mSheet && Servo_StyleSheet_HasRules(Inner()->mSheet);
+  return Inner()->mContents && Servo_StyleSheet_HasRules(Inner()->mContents);
 }
 
 nsresult
@@ -159,23 +159,11 @@ ServoStyleSheet::ParseSheet(css::Loader* aLoader,
     new URLExtraData(aBaseURI, aSheetURI, aSheetPrincipal);
 
   NS_ConvertUTF16toUTF8 input(aInput);
-  if (!Inner()->mSheet) {
-    auto* mediaList = static_cast<ServoMediaList*>(mMedia.get());
-    RawServoMediaList* media = mediaList ?  &mediaList->RawList() : nullptr;
-
-    Inner()->mSheet =
-      Servo_StyleSheet_FromUTF8Bytes(
-          aLoader, this, &input, mParsingMode, media, extraData,
-          aLineNumber, aCompatMode
-      ).Consume();
-  } else {
-    // TODO(emilio): Once we have proper inner cloning (which we don't right
-    // now) we should update the mediaList here too, though it's slightly
-    // tricky.
-    Servo_StyleSheet_ClearAndUpdate(Inner()->mSheet, aLoader,
-                                    this, &input, extraData, aLineNumber,
-                                    aReusableSheets);
-  }
+  Inner()->mContents =
+    Servo_StyleSheet_FromUTF8Bytes(
+        aLoader, this, &input, mParsingMode, extraData,
+        aLineNumber, aCompatMode
+    ).Consume();
 
   Inner()->mURLData = extraData.forget();
   return NS_OK;
@@ -184,11 +172,11 @@ ServoStyleSheet::ParseSheet(css::Loader* aLoader,
 void
 ServoStyleSheet::LoadFailed()
 {
-  if (!Inner()->mSheet) {
+  if (!Inner()->mContents) {
     // Only create empty stylesheet if this is a top level stylesheet.
     // The raw sheet for stylesheet of @import rule is already set in
     // loader, and we should not touch it.
-    Inner()->mSheet = Servo_StyleSheet_Empty(mParsingMode).Consume();
+    Inner()->mContents = Servo_StyleSheet_Empty(mParsingMode).Consume();
   }
   Inner()->mURLData = URLExtraData::Dummy();
 }
@@ -354,7 +342,7 @@ ServoStyleSheet::GetCssRulesInternal()
     EnsureUniqueInner();
 
     RefPtr<ServoCssRules> rawRules =
-      Servo_StyleSheet_GetRules(Inner()->mSheet).Consume();
+      Servo_StyleSheet_GetRules(Inner()->mContents).Consume();
     MOZ_ASSERT(rawRules);
     mRuleList = new ServoCSSRuleList(rawRules.forget(), this);
   }
diff --git a/layout/style/ServoStyleSheet.h b/layout/style/ServoStyleSheet.h
index 007298abe2e2..e43d39ad67a2 100644
--- a/layout/style/ServoStyleSheet.h
+++ b/layout/style/ServoStyleSheet.h
@@ -29,7 +29,7 @@ class LoaderReusableStyleSheets;
 // Servo Style Sheet Inner Data Container
 //
 
-struct ServoStyleSheetInner : public StyleSheetInfo
+struct ServoStyleSheetInner final : public StyleSheetInfo
 {
   ServoStyleSheetInner(CORSMode aCORSMode,
                        ReferrerPolicy aReferrerPolicy,
@@ -42,7 +42,8 @@ struct ServoStyleSheetInner : public StyleSheetInfo
 
   size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) const;
 
-  RefPtr<const RawServoStyleSheet> mSheet;
+  RefPtr<const RawServoStyleSheetContents> mContents;
+
   // XXX StyleSheetInfo already has mSheetURI, mBaseURI, and mPrincipal.
   // Can we somehow replace them with URLExtraData directly? The issue
   // is currently URLExtraData is immutable, but URIs in StyleSheetInfo
@@ -97,12 +98,13 @@ public:
 
   nsresult ReparseSheet(const nsAString& aInput);
 
-  const RawServoStyleSheet* RawSheet() const {
-    return Inner()->mSheet;
+  const RawServoStyleSheetContents* RawContents() const {
+    return Inner()->mContents;
   }
-  void SetSheetForImport(const RawServoStyleSheet* aSheet) {
-    MOZ_ASSERT(!Inner()->mSheet);
-    Inner()->mSheet = aSheet;
+
+  void SetContentsForImport(const RawServoStyleSheetContents* aContents) {
+    MOZ_ASSERT(!Inner()->mContents);
+    Inner()->mContents = aContents;
   }
 
   URLExtraData* URLData() const { return Inner()->mURLData; }
diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index abc89d459692..20e21962f357 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -3698,9 +3698,7 @@ CSSParserImpl::ProcessImport(const nsString& aURLSpec,
   }
 
   if (mChildLoader) {
-    mChildLoader->LoadChildSheet(mSheet, url, aMedia, rule,
-                                 /* aServoParentRule = */ nullptr,
-                                 mReusableSheets);
+    mChildLoader->LoadChildSheet(mSheet, url, aMedia, rule, mReusableSheets);
   }
 }
 
diff --git a/layout/style/test/gtest/StyloParsingBench.cpp b/layout/style/test/gtest/StyloParsingBench.cpp
index 0e8d16ad1f26..3558c8779395 100644
--- a/layout/style/test/gtest/StyloParsingBench.cpp
+++ b/layout/style/test/gtest/StyloParsingBench.cpp
@@ -27,10 +27,11 @@ static void ServoParsingBench() {
   RefPtr<URLExtraData> data = new URLExtraData(
     NullPrincipalURI::Create(), nullptr, NullPrincipal::Create());
   for (int i = 0; i < PARSING_REPETITIONS; i++) {
-    RefPtr<RawServoStyleSheet> stylesheet = Servo_StyleSheet_FromUTF8Bytes(
-      nullptr, nullptr, &css, eAuthorSheetFeatures, nullptr,
-      data, 0, eCompatibility_FullStandards
-    ).Consume();
+    RefPtr<RawServoStyleSheetContents> stylesheet =
+      Servo_StyleSheet_FromUTF8Bytes(
+        nullptr, nullptr, &css, eAuthorSheetFeatures,
+        data, 0, eCompatibility_FullStandards
+      ).Consume();
   }
 }