--- a/dom/animation/EffectCompositor.h
+++ b/dom/animation/EffectCompositor.h
@@ -55,22 +55,22 @@ public:
   NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(EffectCompositor)
   NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(EffectCompositor)
 
   void Disconnect() {
     mPresContext = nullptr;
   }
 
   // Animations can be applied at two different levels in the CSS cascade:
-  enum class CascadeLevel {
+  enum class CascadeLevel : uint32_t {
     // The animations sheet (CSS animations, script-generated animations,
     // and CSS transitions that are no longer tied to CSS markup)
-    Animations,
+    Animations = 0,
     // The transitions sheet (CSS transitions that are tied to CSS markup)
-    Transitions
+    Transitions = 1
   };
   // We don't define this as part of CascadeLevel as then we'd have to add
   // explicit checks for the Count enum value everywhere CascadeLevel is used.
   static const size_t kCascadeLevelCount =
     static_cast<size_t>(CascadeLevel::Transitions) + 1;
 
   // NOTE: This can return null after Disconnect().
   nsPresContext* PresContext() const { return mPresContext; }

--- a/layout/style/ServoBindings.cpp
+++ b/layout/style/ServoBindings.cpp
@@ -324,48 +324,46 @@ Gecko_GetServoDeclarationBlock(RawGeckoE
     return nullptr;
   }
   return reinterpret_cast<const RawServoDeclarationBlockStrong*>
     (decl->AsServo()->RefRaw());
 }
 
 RawServoDeclarationBlockStrong
 Gecko_GetAnimationRule(RawGeckoElementBorrowed aElement,
-                       nsIAtom* aPseudoTag)
+                       nsIAtom* aPseudoTag,
+                       EffectCompositor::CascadeLevel aCascadeLevel)
 {
   MOZ_ASSERT(aElement, "Invalid GeckoElement");
 
   const RawServoDeclarationBlockStrong emptyDeclarationBlock{ nullptr };
   nsIDocument* doc = aElement->GetComposedDoc();
   if (!doc || !doc->GetShell()) {
     return emptyDeclarationBlock;
   }
   nsPresContext* presContext = doc->GetShell()->GetPresContext();
   if (!presContext) {
     return emptyDeclarationBlock;
   }
 
-  // FIXME: support different cascading levels in the later patch
   CSSPseudoElementType pseudoType =
     aPseudoTag
     ? nsCSSPseudoElements::GetPseudoType(
         aPseudoTag,
         nsCSSProps::EnabledState::eIgnoreEnabledState)
     : CSSPseudoElementType::NotPseudo;
   if (pseudoType != CSSPseudoElementType::NotPseudo &&
       pseudoType != CSSPseudoElementType::before &&
       pseudoType != CSSPseudoElementType::after) {
     return emptyDeclarationBlock;
   }
 
   ServoAnimationRule* rule =
-    presContext->EffectCompositor()->GetServoAnimationRule(
-      aElement,
-      pseudoType,
-      EffectCompositor::CascadeLevel::Animations);
+    presContext->EffectCompositor()
+               ->GetServoAnimationRule(aElement, pseudoType, aCascadeLevel);
   if (!rule) {
     return emptyDeclarationBlock;
   }
   return rule->GetValues();
 }
 
 void
 Gecko_FillAllBackgroundLists(nsStyleImageLayers* aLayers, uint32_t aMaxLen)

--- a/layout/style/ServoBindings.h
+++ b/layout/style/ServoBindings.h
@@ -8,16 +8,17 @@
 #define mozilla_ServoBindings_h
 
 #include <stdint.h>
 
 #include "mozilla/ServoTypes.h"
 #include "mozilla/ServoBindingTypes.h"
 #include "mozilla/ServoElementSnapshot.h"
 #include "mozilla/css/SheetParsingMode.h"
+#include "mozilla/EffectCompositor.h"
 #include "nsChangeHint.h"
 #include "nsCSSPseudoClasses.h"
 #include "nsStyleStruct.h"
 
 /*
  * API for Servo to access Gecko data structures. This file must compile as valid
  * C code in order for the binding generator to parse it.
  *
@@ -156,17 +157,18 @@ SERVO_DECLARE_ELEMENT_ATTR_MATCHING_FUNC
 
 // Style attributes.
 RawServoDeclarationBlockStrongBorrowedOrNull
 Gecko_GetServoDeclarationBlock(RawGeckoElementBorrowed element);
 
 // Animations
 RawServoDeclarationBlockStrong
 Gecko_GetAnimationRule(RawGeckoElementBorrowed aElement,
-                       nsIAtom* aPseudoTag);
+                       nsIAtom* aPseudoTag,
+                       mozilla::EffectCompositor::CascadeLevel aCascadeLevel);
 
 // Atoms.
 nsIAtom* Gecko_Atomize(const char* aString, uint32_t aLength);
 void Gecko_AddRefAtom(nsIAtom* aAtom);
 void Gecko_ReleaseAtom(nsIAtom* aAtom);
 const uint16_t* Gecko_GetAtomAsUTF16(nsIAtom* aAtom, uint32_t* aLength);
 bool Gecko_AtomEqualsUTF8(nsIAtom* aAtom, const char* aString, uint32_t aLength);
 bool Gecko_AtomEqualsUTF8IgnoreCase(nsIAtom* aAtom, const char* aString, uint32_t aLength);