diff --git a/layout/generic/BlockReflowInput.cpp b/layout/generic/BlockReflowInput.cpp
index 19f6d785522d..3113ce9f18ad 100644
--- a/layout/generic/BlockReflowInput.cpp
+++ b/layout/generic/BlockReflowInput.cpp
@@ -264,13 +264,13 @@ BlockReflowInput::ComputeBlockAvailSpace(nsIFrame* aFrame,
       const nsStyleBorder* borderStyle = aFrame->StyleBorder();
       switch (borderStyle->mFloatEdge) {
         default:
-        case NS_STYLE_FLOAT_EDGE_CONTENT_BOX:  // content and only content does runaround of floats
+        case StyleFloatEdge::ContentBox:  // content and only content does runaround of floats
           // The child block will flow around the float. Therefore
           // give it all of the available space.
           aResult.IStart(wm) = mContentArea.IStart(wm);
           aResult.ISize(wm) = mContentArea.ISize(wm);
           break;
-        case NS_STYLE_FLOAT_EDGE_MARGIN_BOX:
+        case StyleFloatEdge::MarginBox:
           {
             // The child block's margins should be placed adjacent to,
             // but not overlap the float.
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index 0b80a78bcc05..f1c0bf68a34b 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -1491,8 +1491,8 @@ KTableEntry nsCSSProps::kFloatKTable[] = {
 };
 
 const KTableEntry nsCSSProps::kFloatEdgeKTable[] = {
-  { eCSSKeyword_content_box, NS_STYLE_FLOAT_EDGE_CONTENT_BOX },
-  { eCSSKeyword_margin_box, NS_STYLE_FLOAT_EDGE_MARGIN_BOX },
+  { eCSSKeyword_content_box, uint8_t(StyleFloatEdge::ContentBox) },
+  { eCSSKeyword_margin_box, uint8_t(StyleFloatEdge::MarginBox) },
   { eCSSKeyword_UNKNOWN, -1 }
 };
 
diff --git a/layout/style/nsComputedDOMStyle.cpp b/layout/style/nsComputedDOMStyle.cpp
index 29f2a71ceaab..7c951787fd19 100644
--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -4404,7 +4404,7 @@ nsComputedDOMStyle::DoGetFloatEdge()
 {
   RefPtr<nsROCSSPrimitiveValue> val = new nsROCSSPrimitiveValue;
   val->SetIdent(
-    nsCSSProps::ValueToKeywordEnum(StyleBorder()->mFloatEdge,
+    nsCSSProps::ValueToKeywordEnum(uint8_t(StyleBorder()->mFloatEdge),
                                    nsCSSProps::kFloatEdgeKTable));
   return val.forget();
 }
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index cafa06de47bd..ae2afc16aa9c 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -1301,6 +1301,7 @@ struct SetEnumValueHelper
   }
 
   DEFINE_ENUM_CLASS_SETTER(StyleBoxSizing, Content, Border)
+  DEFINE_ENUM_CLASS_SETTER(StyleFloatEdge, ContentBox, MarginBox)
 
 #undef DEF_SET_ENUMERATED_VALUE
 };
@@ -7578,7 +7579,7 @@ nsRuleNode::ComputeBorderData(void* aStartStruct,
            border->mFloatEdge, conditions,
            SETVAL_ENUMERATED | SETVAL_UNSET_INITIAL,
            parentBorder->mFloatEdge,
-           NS_STYLE_FLOAT_EDGE_CONTENT_BOX);
+           StyleFloatEdge::ContentBox);
 
   // border-image-source
   const nsCSSValue* borderImageSource = aRuleData->ValueForBorderImageSource();
diff --git a/layout/style/nsStyleConsts.h b/layout/style/nsStyleConsts.h
index e9b65d39d254..dc5d13c51908 100644
--- a/layout/style/nsStyleConsts.h
+++ b/layout/style/nsStyleConsts.h
@@ -95,8 +95,10 @@ enum class StyleClipShapeSizing : uint8_t {
 };
 
 // float-edge
-#define NS_STYLE_FLOAT_EDGE_CONTENT_BOX    0
-#define NS_STYLE_FLOAT_EDGE_MARGIN_BOX     1
+enum class StyleFloatEdge : uint8_t {
+  ContentBox,
+  MarginBox,
+};
 
 // user-focus
 #define NS_STYLE_USER_FOCUS_NONE            0
diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index ab23b37ae9f5..595c8d19f81d 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -332,7 +332,7 @@ nsStyleBorder::nsStyleBorder(StyleStructContext aContext)
   , mBorderImageFill(NS_STYLE_BORDER_IMAGE_SLICE_NOFILL)
   , mBorderImageRepeatH(NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH)
   , mBorderImageRepeatV(NS_STYLE_BORDER_IMAGE_REPEAT_STRETCH)
-  , mFloatEdge(NS_STYLE_FLOAT_EDGE_CONTENT_BOX)
+  , mFloatEdge(StyleFloatEdge::ContentBox)
   , mBoxDecorationBreak(NS_STYLE_BOX_DECORATION_BREAK_SLICE)
   , mComputedBorder(0, 0, 0, 0)
 {
@@ -2855,7 +2855,7 @@ StyleTransition::SetUnknownProperty(nsCSSProperty aProperty,
 }
 
 bool
-StyleTransition::operator==(const mozilla::StyleTransition& aOther) const
+StyleTransition::operator==(const StyleTransition& aOther) const
 {
   return mTimingFunction == aOther.mTimingFunction &&
          mDuration == aOther.mDuration &&
@@ -2865,7 +2865,7 @@ StyleTransition::operator==(const mozilla::StyleTransition& aOther) const
           mUnknownProperty == aOther.mUnknownProperty);
 }
 
-StyleAnimation::StyleAnimation(const mozilla::StyleAnimation& aCopy)
+StyleAnimation::StyleAnimation(const StyleAnimation& aCopy)
   : mTimingFunction(aCopy.mTimingFunction)
   , mDuration(aCopy.mDuration)
   , mDelay(aCopy.mDelay)
@@ -2891,7 +2891,7 @@ StyleAnimation::SetInitialValues()
 }
 
 bool
-StyleAnimation::operator==(const mozilla::StyleAnimation& aOther) const
+StyleAnimation::operator==(const StyleAnimation& aOther) const
 {
   return mTimingFunction == aOther.mTimingFunction &&
          mDuration == aOther.mDuration &&
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index 98d370a5b859..2a26f028bd90 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -1260,7 +1260,7 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleBorder
   }
 
 public:
-  nsBorderColors** mBorderColors;        // [reset] composite (stripe) colors
+  nsBorderColors** mBorderColors;     // [reset] composite (stripe) colors
   nsStyleCorners mBorderRadius;       // [reset] coord, percent
   nsStyleImage   mBorderImageSource;  // [reset]
   nsStyleSides   mBorderImageSlice;   // [reset] factor, percent
@@ -1270,7 +1270,7 @@ public:
   uint8_t        mBorderImageFill;    // [reset]
   uint8_t        mBorderImageRepeatH; // [reset] see nsStyleConsts.h
   uint8_t        mBorderImageRepeatV; // [reset]
-  uint8_t        mFloatEdge;          // [reset]
+  mozilla::StyleFloatEdge mFloatEdge; // [reset]
   uint8_t        mBoxDecorationBreak; // [reset] see nsStyleConsts.h
 
 protected: