diff --git a/content/base/src/nsRuleNode.cpp b/content/base/src/nsRuleNode.cpp
index 859041a81fd9..aee9309ad058 100644
--- a/content/base/src/nsRuleNode.cpp
+++ b/content/base/src/nsRuleNode.cpp
@@ -577,35 +577,43 @@ struct StructCheckData {
   CheckCallbackFn callback;
 };
 
-static void
-ExamineRectProperties(const nsCSSRect* aRect,
-                      PRUint32& aSpecifiedCount, PRUint32& aInheritedCount)
+
+/**
+ * @param aValue the value being examined
+ * @param aSpecifiedCount to be incremented by one if the value is specified
+ * @param aInherited to be incremented by one if the value is set to inherit
+ */
+inline void
+ExamineCSSValue(const nsCSSValue& aValue,
+                PRUint32& aSpecifiedCount, PRUint32& aInheritedCount)
 {
-  if (!aRect)
-    return;
-
-  if (eCSSUnit_Null != aRect->mLeft.GetUnit()) {
-    aSpecifiedCount++;
-    if (eCSSUnit_Inherit == aRect->mLeft.GetUnit())
-      aInheritedCount++;
+  if (aValue.GetUnit() != eCSSUnit_Null) {
+    ++aSpecifiedCount;
+    if (aValue.GetUnit() == eCSSUnit_Inherit) {
+      ++aInheritedCount;
+    }
   }
+}
 
-  if (eCSSUnit_Null != aRect->mTop.GetUnit()) {
-    aSpecifiedCount++;
-    if (eCSSUnit_Inherit == aRect->mTop.GetUnit())
-      aInheritedCount++;
-  }
+static void
+ExamineCSSValuePair(const nsCSSValuePair* aValuePair,
+                    PRUint32& aSpecifiedCount, PRUint32& aInheritedCount)
+{
+  NS_PRECONDITION(aValuePair, "Must have a value pair");
+  
+  ExamineCSSValue(aValuePair->mXValue, aSpecifiedCount, aInheritedCount);
+  ExamineCSSValue(aValuePair->mYValue, aSpecifiedCount, aInheritedCount);
+}
 
-  if (eCSSUnit_Null != aRect->mRight.GetUnit()) {
-    aSpecifiedCount++;
-    if (eCSSUnit_Inherit == aRect->mRight.GetUnit())
-      aInheritedCount++;
-  }
+static void
+ExamineCSSRect(const nsCSSRect* aRect,
+               PRUint32& aSpecifiedCount, PRUint32& aInheritedCount)
+{
+  NS_PRECONDITION(aRect, "Must have a rect");
 
-  if (eCSSUnit_Null != aRect->mBottom.GetUnit()) {
-    aSpecifiedCount++;
-    if (eCSSUnit_Inherit == aRect->mBottom.GetUnit())
-      aInheritedCount++;
+  NS_FOR_CSS_SIDES(side) {
+    ExamineCSSValue(aRect->*(nsCSSRect::sides[side]),
+                    aSpecifiedCount, aInheritedCount);
   }
 }
 
@@ -840,6 +848,13 @@ RectAtOffset(const nsRuleDataStruct& aRuleDataStruct, size_t aOffset)
                      NS_REINTERPRET_CAST(const char*, &aRuleDataStruct) + aOffset);
 }
 
+inline const nsCSSValuePair*
+ValuePairAtOffset(const nsRuleDataStruct& aRuleDataStruct, size_t aOffset)
+{
+  return NS_REINTERPRET_CAST(const nsCSSValuePair*,
+                     NS_REINTERPRET_CAST(const char*, &aRuleDataStruct) + aOffset);
+}
+
 inline const nsCSSValueList*
 ValueListAtOffset(const nsRuleDataStruct& aRuleDataStruct, size_t aOffset)
 {
@@ -893,24 +908,23 @@ nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
     switch (prop->type) {
 
       case eCSSType_Value:
-        {
-          ++total;
-          const nsCSSValue& value = ValueAtOffset(aRuleDataStruct, prop->offset);
-          if (eCSSUnit_Null != value.GetUnit()) {
-            ++specified;
-            if (eCSSUnit_Inherit == value.GetUnit()) {
-              ++inherited;
-            }
-          }
-        }
+        ++total;
+        ExamineCSSValue(ValueAtOffset(aRuleDataStruct, prop->offset),
+                        specified, inherited);
         break;
 
       case eCSSType_Rect:
         total += 4;
-        ExamineRectProperties(RectAtOffset(aRuleDataStruct, prop->offset),
-                              specified, inherited);
+        ExamineCSSRect(RectAtOffset(aRuleDataStruct, prop->offset),
+                       specified, inherited);
         break;
 
+      case eCSSType_ValuePair:
+        total += 2;
+        ExamineCSSValuePair(ValuePairAtOffset(aRuleDataStruct, prop->offset),
+                            specified, inherited);
+        break;
+        
       case eCSSType_ValueList:
         {
           ++total;
@@ -3827,18 +3841,18 @@ nsRuleNode::ComputeTableBorderData(nsStyleStruct* aStartStruct,
   nsStyleCoord coord;
 
   // border-spacing-x: length, inherit
-  if (SetCoord(tableData.mBorderSpacingX, coord, coord, SETCOORD_LENGTH, aContext, mPresContext, inherited)) {
+  if (SetCoord(tableData.mBorderSpacing.mXValue, coord, coord, SETCOORD_LENGTH, aContext, mPresContext, inherited)) {
     table->mBorderSpacingX = coord.GetCoordValue();
   }
-  else if (eCSSUnit_Inherit == tableData.mBorderSpacingX.GetUnit()) {
+  else if (eCSSUnit_Inherit == tableData.mBorderSpacing.mXValue.GetUnit()) {
     inherited = PR_TRUE;
     table->mBorderSpacingX = parentTable->mBorderSpacingX;
   }
   // border-spacing-y: length, inherit
-  if (SetCoord(tableData.mBorderSpacingY, coord, coord, SETCOORD_LENGTH, aContext, mPresContext, inherited)) {
+  if (SetCoord(tableData.mBorderSpacing.mYValue, coord, coord, SETCOORD_LENGTH, aContext, mPresContext, inherited)) {
     table->mBorderSpacingY = coord.GetCoordValue();
   }
-  else if (eCSSUnit_Inherit == tableData.mBorderSpacingY.GetUnit()) {
+  else if (eCSSUnit_Inherit == tableData.mBorderSpacing.mYValue.GetUnit()) {
     inherited = PR_TRUE;
     table->mBorderSpacingY = parentTable->mBorderSpacingY;
   }
diff --git a/content/html/content/src/nsHTMLTableElement.cpp b/content/html/content/src/nsHTMLTableElement.cpp
index 897e8eca5ea4..b7de668566d5 100644
--- a/content/html/content/src/nsHTMLTableElement.cpp
+++ b/content/html/content/src/nsHTMLTableElement.cpp
@@ -1085,17 +1085,17 @@ MapAttributesIntoRule(const nsMappedAttributes* aAttributes,
       // cellspacing 
       const nsAttrValue* value = aAttributes->GetAttr(nsHTMLAtoms::cellspacing);
       if (value && value->Type() == nsAttrValue::eInteger) {
-        if (aData->mTableData->mBorderSpacingX.GetUnit() == eCSSUnit_Null)
-          aData->mTableData->mBorderSpacingX.SetFloatValue((float)value->GetIntegerValue(), eCSSUnit_Pixel);
-        if (aData->mTableData->mBorderSpacingY.GetUnit() == eCSSUnit_Null)
-          aData->mTableData->mBorderSpacingY.SetFloatValue((float)value->GetIntegerValue(), eCSSUnit_Pixel);
+        if (aData->mTableData->mBorderSpacing.mXValue.GetUnit() == eCSSUnit_Null)
+          aData->mTableData->mBorderSpacing.mXValue.SetFloatValue((float)value->GetIntegerValue(), eCSSUnit_Pixel);
+        if (aData->mTableData->mBorderSpacing.mYValue.GetUnit() == eCSSUnit_Null)
+          aData->mTableData->mBorderSpacing.mYValue.SetFloatValue((float)value->GetIntegerValue(), eCSSUnit_Pixel);
       }
       else if (value && value->Type() == nsAttrValue::ePercent && eCompatibility_NavQuirks == mode) {
         // in quirks mode, treat a % cellspacing value a pixel value.
-        if (aData->mTableData->mBorderSpacingX.GetUnit() == eCSSUnit_Null)
-          aData->mTableData->mBorderSpacingX.SetFloatValue(100.0f * value->GetPercentValue(), eCSSUnit_Pixel);
-        if (aData->mTableData->mBorderSpacingY.GetUnit() == eCSSUnit_Null)
-          aData->mTableData->mBorderSpacingY.SetFloatValue(100.0f * value->GetPercentValue(), eCSSUnit_Pixel);
+        if (aData->mTableData->mBorderSpacing.mXValue.GetUnit() == eCSSUnit_Null)
+          aData->mTableData->mBorderSpacing.mXValue.SetFloatValue(100.0f * value->GetPercentValue(), eCSSUnit_Pixel);
+        if (aData->mTableData->mBorderSpacing.mYValue.GetUnit() == eCSSUnit_Null)
+          aData->mTableData->mBorderSpacing.mYValue.SetFloatValue(100.0f * value->GetPercentValue(), eCSSUnit_Pixel);
       }
     }
   } 
diff --git a/content/html/style/src/nsCSSDataBlock.cpp b/content/html/style/src/nsCSSDataBlock.cpp
index c54e613855cb..d33701220938 100644
--- a/content/html/style/src/nsCSSDataBlock.cpp
+++ b/content/html/style/src/nsCSSDataBlock.cpp
@@ -1,3 +1,4 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
@@ -66,6 +67,11 @@ struct CDBRectStorage {
 
 };
 
+struct CDBValuePairStorage {
+    nsCSSProperty property;
+    nsCSSValuePair value;
+};
+
 struct CDBPointerStorage {
     nsCSSProperty property;
     void *value;
@@ -74,6 +80,7 @@ struct CDBPointerStorage {
 enum {
     CDBValueStorage_advance = sizeof(CDBValueStorage),
     CDBRectStorage_advance = sizeof(CDBRectStorage),
+    CDBValuePairStorage_advance = sizeof(CDBValuePairStorage),
     // round up using the closest estimate we can get of the alignment
     // requirements of nsCSSValue:
     CDBPointerStorage_advance = PR_ROUNDUP(sizeof(CDBPointerStorage),
@@ -112,6 +119,14 @@ inline const nsCSSRect* RectAtCursor(const char *aCursor) {
     return & NS_REINTERPRET_CAST(const CDBRectStorage*, aCursor)->value;
 }
 
+inline nsCSSValuePair* ValuePairAtCursor(char *aCursor) {
+  return & NS_REINTERPRET_CAST(CDBValuePairStorage*, aCursor)->value;
+}
+
+inline const nsCSSValuePair* ValuePairAtCursor(const char *aCursor) {
+  return & NS_REINTERPRET_CAST(const CDBValuePairStorage*, aCursor)->value;
+}
+
 inline void*& PointerAtCursor(char *aCursor) {
     return NS_REINTERPRET_CAST(CDBPointerStorage*, aCursor)->value;
 }
@@ -215,6 +230,18 @@ nsCSSCompressedDataBlock::MapRuleInfoInto(nsRuleData *aRuleData) const
                     cursor += CDBRectStorage_advance;
                 } break;
 
+                case eCSSType_ValuePair: {
+                    const nsCSSValuePair* val = ValuePairAtCursor(cursor);
+                    NS_ASSERTION(val->mXValue.GetUnit() != eCSSUnit_Null ||
+                                 val->mYValue.GetUnit() != eCSSUnit_Null, "oops");
+                    nsCSSValuePair* target = NS_STATIC_CAST(nsCSSValuePair*, prop);
+                    if (target->mXValue.GetUnit() == eCSSUnit_Null)
+                        target->mXValue = val->mXValue;
+                    if (target->mYValue.GetUnit() == eCSSUnit_Null)
+                        target->mYValue = val->mYValue;
+                    cursor += CDBValuePairStorage_advance;
+                } break;
+
                 case eCSSType_ValueList:
                     if (iProp == eCSSProperty_content) {
                         for (nsCSSValueList* l = ValueListAtCursor(cursor);
@@ -246,6 +273,10 @@ nsCSSCompressedDataBlock::MapRuleInfoInto(nsRuleData *aRuleData) const
                     cursor += CDBRectStorage_advance;
                 } break;
 
+                case eCSSType_ValuePair: {
+                    cursor += CDBValuePairStorage_advance;
+                } break;
+
                 case eCSSType_ValueList:
                 case eCSSType_CounterData:
                 case eCSSType_Quotes:
@@ -285,6 +316,9 @@ nsCSSCompressedDataBlock::StorageFor(nsCSSProperty aProperty) const
                 case eCSSType_Rect: {
                     return RectAtCursor(cursor);
                 }
+                case eCSSType_ValuePair: {
+                    return ValuePairAtCursor(cursor);
+                }
                 case eCSSType_ValueList:
                 case eCSSType_CounterData:
                 case eCSSType_Quotes:
@@ -302,6 +336,10 @@ nsCSSCompressedDataBlock::StorageFor(nsCSSProperty aProperty) const
                 cursor += CDBRectStorage_advance;
             } break;
 
+            case eCSSType_ValuePair: {
+                cursor += CDBValuePairStorage_advance;
+            } break;
+
             case eCSSType_ValueList:
             case eCSSType_CounterData:
             case eCSSType_Quotes:
@@ -352,6 +390,16 @@ nsCSSCompressedDataBlock::Clone() const
                 result_cursor += CDBRectStorage_advance;
             } break;
 
+            case eCSSType_ValuePair: {
+                const nsCSSValuePair* val = ValuePairAtCursor(cursor);
+                NS_ASSERTION(val->mXValue.GetUnit() != eCSSUnit_Null ||
+                             val->mYValue.GetUnit() != eCSSUnit_Null, "oops");
+                nsCSSValuePair* result_val = ValuePairAtCursor(result_cursor);
+                new (result_val) nsCSSValuePair(*val);
+                cursor += CDBValuePairStorage_advance;
+                result_cursor += CDBValuePairStorage_advance;
+            } break;
+
             case eCSSType_ValueList:
             case eCSSType_CounterData:
             case eCSSType_Quotes:
@@ -421,6 +469,14 @@ nsCSSCompressedDataBlock::Destroy()
                 cursor += CDBRectStorage_advance;
             } break;
 
+            case eCSSType_ValuePair: {
+                const nsCSSValuePair* val = ValuePairAtCursor(cursor);
+                NS_ASSERTION(val->mXValue.GetUnit() != eCSSUnit_Null ||
+                             val->mYValue.GetUnit() != eCSSUnit_Null, "oops");
+                val->~nsCSSValuePair();
+                cursor += CDBValuePairStorage_advance;
+            } break;
+
             case eCSSType_ValueList: {
                 nsCSSValueList* val = ValueListAtCursor(cursor);
                 NS_ASSERTION(val, "oops");
@@ -532,6 +588,14 @@ nsCSSExpandedDataBlock::DoExpand(nsCSSCompressedDataBlock *aBlock,
                 cursor += CDBRectStorage_advance;
             } break;
 
+            case eCSSType_ValuePair: {
+                const nsCSSValuePair* val = ValuePairAtCursor(cursor);
+                NS_ASSERTION(val->mXValue.GetUnit() != eCSSUnit_Null ||
+                             val->mYValue.GetUnit() != eCSSUnit_Null, "oops");
+                memcpy(prop, val, sizeof(nsCSSValuePair));
+                cursor += CDBValuePairStorage_advance;
+            } break;
+
             case eCSSType_ValueList:
             case eCSSType_CounterData:
             case eCSSType_Quotes:
@@ -594,6 +658,14 @@ nsCSSExpandedDataBlock::ComputeSize()
                     }
                 } break;
 
+                case eCSSType_ValuePair: {
+                    nsCSSValuePair* val = NS_STATIC_CAST(nsCSSValuePair*, prop);
+                    if (val->mXValue.GetUnit() != eCSSUnit_Null ||
+                        val->mYValue.GetUnit() != eCSSUnit_Null) {
+                        increment = CDBValuePairStorage_advance;
+                    }
+                } break;
+
                 case eCSSType_ValueList:
                 case eCSSType_CounterData:
                 case eCSSType_Quotes:
@@ -692,6 +764,20 @@ nsCSSExpandedDataBlock::Compress(nsCSSCompressedDataBlock **aNormalBlock,
                     }
                 } break;
 
+                case eCSSType_ValuePair: {
+                    nsCSSValuePair* val = NS_STATIC_CAST(nsCSSValuePair*, prop);
+                    if (val->mXValue.GetUnit() != eCSSUnit_Null ||
+                        val->mYValue.GetUnit() != eCSSUnit_Null) {
+                        CDBValuePairStorage *storage =
+                            NS_REINTERPRET_CAST(CDBValuePairStorage*, cursor);
+                        storage->property = iProp;
+                        memcpy(&storage->value, val, sizeof(nsCSSValuePair));
+                        new (val) nsCSSValuePair();
+                        cursor += CDBValuePairStorage_advance;
+                        present = PR_TRUE;
+                    }
+                } break;
+
                 case eCSSType_ValueList:
                 case eCSSType_CounterData:
                 case eCSSType_Quotes:
@@ -769,6 +855,12 @@ nsCSSExpandedDataBlock::ClearProperty(nsCSSProperty aPropID)
             val->Reset();
         } break;
 
+        case eCSSType_ValuePair: {
+            nsCSSValuePair* val = NS_STATIC_CAST(nsCSSValuePair*, prop);
+            val->mXValue.Reset();
+            val->mYValue.Reset();
+        } break;
+
         case eCSSType_ValueList: {
             nsCSSValueList*& val = *NS_STATIC_CAST(nsCSSValueList**, prop);
             if (val) {
@@ -837,6 +929,14 @@ nsCSSExpandedDataBlock::DoAssertInitialState()
                              "not initial state");
             } break;
 
+            case eCSSType_ValuePair: {
+                nsCSSValuePair* val = NS_STATIC_CAST(nsCSSValuePair*, prop);
+                NS_ASSERTION(val->mXValue.GetUnit() == eCSSUnit_Null,
+                             "not initial state");
+                NS_ASSERTION(val->mYValue.GetUnit() == eCSSUnit_Null,
+                             "not initial state");
+            } break;
+
             case eCSSType_ValueList: {
                 nsCSSValueList* val = *NS_STATIC_CAST(nsCSSValueList**, prop);
                 NS_ASSERTION(val == nsnull, "not initial state");
diff --git a/content/html/style/src/nsCSSDeclaration.cpp b/content/html/style/src/nsCSSDeclaration.cpp
index 46a5b2eec2b3..671b7c3c3489 100644
--- a/content/html/style/src/nsCSSDeclaration.cpp
+++ b/content/html/style/src/nsCSSDeclaration.cpp
@@ -40,6 +40,7 @@
 #include "nsString.h"
 #include "nsIAtom.h"
 #include "nsUnicharUtils.h"
+#include "nsReadableUtils.h"
 #include "nsCRT.h"
 #include "nsCSSProps.h"
 #include "nsUnitConversion.h"
@@ -214,6 +215,15 @@ PRBool nsCSSDeclaration::AppendValueToString(nsCSSProperty aProperty, nsAString&
           aResult.Append(PRUnichar(')'));
         }
       } break;
+      case eCSSType_ValuePair: {
+        const nsCSSValuePair *pair = NS_STATIC_CAST(const nsCSSValuePair*, storage);
+        AppendCSSValueToString(aProperty, pair->mXValue, aResult);
+        if (pair->mYValue != pair->mXValue) {
+          // Only output a Y value if it's different from the X value
+          aResult.Append(PRUnichar(' '));
+          AppendCSSValueToString(aProperty, pair->mYValue, aResult);
+        }
+      } break;
       case eCSSType_ValueList: {
         const nsCSSValueList* val =
             *NS_STATIC_CAST(nsCSSValueList*const*, storage);
@@ -364,18 +374,6 @@ PRBool nsCSSDeclaration::AppendCSSValueToString(nsCSSProperty aProperty, const n
         AppendASCIItoUTF16(nsCSSProps::LookupPropertyValue(aProperty, NS_STYLE_AZIMUTH_BEHIND), aResult);
       }
     }
-    else if (eCSSProperty_play_during_flags == aProperty) {
-      PRInt32 intValue = aValue.GetIntValue();
-      if ((NS_STYLE_PLAY_DURING_MIX & intValue) != 0) {
-        AppendASCIItoUTF16(nsCSSProps::LookupPropertyValue(aProperty, NS_STYLE_PLAY_DURING_MIX), aResult);
-      }
-      if ((NS_STYLE_PLAY_DURING_REPEAT & intValue) != 0) {
-        if (NS_STYLE_PLAY_DURING_REPEAT != intValue) {
-          aResult.Append(PRUnichar(' '));
-        }
-        AppendASCIItoUTF16(nsCSSProps::LookupPropertyValue(aProperty, NS_STYLE_PLAY_DURING_REPEAT), aResult);
-      }
-    }
     else if (eCSSProperty_marks == aProperty) {
       PRInt32 intValue = aValue.GetIntValue();
       if ((NS_STYLE_PAGE_MARKS_CROP & intValue) != 0) {
@@ -493,7 +491,9 @@ nsCSSDeclaration::GetValue(nsCSSProperty aProperty,
   aValue.Truncate(0);
 
   // simple properties are easy.
-  if (!nsCSSProps::IsShorthand(aProperty)) {
+  if (!nsCSSProps::IsShorthand(aProperty) &&
+      // play-during is not a real shorthand, but is special...
+      aProperty != eCSSProperty_play_during) {
     AppendValueToString(aProperty, aValue);
     return NS_OK;
   }
@@ -584,16 +584,6 @@ nsCSSDeclaration::GetValue(nsCSSProperty aProperty,
       }
       break;
     }
-    case eCSSProperty_border_spacing:
-      if (AppendValueToString(eCSSProperty_border_x_spacing, aValue)) {
-        aValue.Append(PRUnichar(' '));
-#ifdef DEBUG
-        PRBool check =
-#endif
-          AppendValueToString(eCSSProperty_border_y_spacing, aValue);
-        NS_ASSERTION(check, "we parsed half of border-spacing");
-      }
-      break;
     case eCSSProperty_cue: {
       if (AppendValueToString(eCSSProperty_cue_after, aValue)) {
         aValue.Append(PRUnichar(' '));
@@ -646,14 +636,6 @@ nsCSSDeclaration::GetValue(nsCSSProperty aProperty,
       }
       break;
     }
-    case eCSSProperty_size: {
-      if (AppendValueToString(eCSSProperty_size_width, aValue)) {
-        aValue.Append(PRUnichar(' '));
-        if (!AppendValueToString(eCSSProperty_size_height, aValue))
-          aValue.Truncate();
-      }
-      break;
-    }
     case eCSSProperty_background_position: {
       if (AppendValueToString(eCSSProperty_background_x_position, aValue)) {
         aValue.Append(PRUnichar(' '));
@@ -666,11 +648,32 @@ nsCSSDeclaration::GetValue(nsCSSProperty aProperty,
       break;
     }
     case eCSSProperty_play_during: {
-      if (AppendValueToString(eCSSProperty_play_during_uri, aValue)) {
-        nsAutoString tmp;
-        if (AppendValueToString(eCSSProperty_play_during_flags, tmp)) {
-          aValue.Append(PRUnichar(' '));
-          aValue.Append(tmp);
+      nsCSSCompressedDataBlock *data =
+        GetValueIsImportant(eCSSProperty_play_during) ? mImportantData : mData;
+      const void *storage = data->StorageFor(eCSSProperty_play_during);
+      if (!storage) {
+        break;
+      }
+      NS_ASSERTION(nsCSSProps::kTypeTable[eCSSProperty_play_during] ==
+                   eCSSType_ValuePair,
+                   "Someone changed the storage type of play-during!");
+      const nsCSSValuePair *pair = NS_STATIC_CAST(const nsCSSValuePair*, storage);
+      AppendCSSValueToString(aProperty, pair->mXValue, aValue);
+      if (pair->mYValue != eCSSUnit_Null) {
+        aValue.Append(PRUnichar(' '));
+        PRInt32 intValue = pair->mYValue.GetIntValue();
+        if ((NS_STYLE_PLAY_DURING_MIX & intValue) != 0) {
+          AppendUTF8toUTF16(nsCSSProps::LookupPropertyValue(aProperty,
+                                                     NS_STYLE_PLAY_DURING_MIX),
+                            aValue);
+        }
+        if ((NS_STYLE_PLAY_DURING_REPEAT & intValue) != 0) {
+          if (NS_STYLE_PLAY_DURING_REPEAT != intValue) {
+            aValue.Append(PRUnichar(' '));
+          }
+          AppendUTF8toUTF16(nsCSSProps::LookupPropertyValue(aProperty,
+                                                  NS_STYLE_PLAY_DURING_REPEAT),
+                            aValue);
         }
       }
       break;
diff --git a/content/html/style/src/nsCSSParser.cpp b/content/html/style/src/nsCSSParser.cpp
index 4f39655dab6d..fd4e766ee153 100644
--- a/content/html/style/src/nsCSSParser.cpp
+++ b/content/html/style/src/nsCSSParser.cpp
@@ -3223,6 +3223,16 @@ CSSParserImpl::DoTransferTempData(nsCSSDeclaration* aDeclaration,
       new (source) nsCSSRect();
     } break;
 
+    case eCSSType_ValuePair: {
+      nsCSSValuePair *source = NS_STATIC_CAST(nsCSSValuePair*, v_source);
+      nsCSSValuePair *dest = NS_STATIC_CAST(nsCSSValuePair*, v_dest);
+      if (*source != *dest)
+        *aChanged = PR_TRUE;
+      dest->~nsCSSValuePair();
+      memcpy(dest, source, sizeof(nsCSSValuePair));
+      new (source) nsCSSValuePair();
+    } break;
+
     case eCSSType_ValueList: {
       nsCSSValueList **source = NS_STATIC_CAST(nsCSSValueList**, v_source);
       nsCSSValueList **dest = NS_STATIC_CAST(nsCSSValueList**, v_dest);
@@ -4060,12 +4070,6 @@ PRBool CSSParserImpl::ParseProperty(nsresult& aErrorCode,
   // by compound property parsing routines (e.g. "background-position").
   case eCSSProperty_background_x_position:
   case eCSSProperty_background_y_position:
-  case eCSSProperty_border_x_spacing:
-  case eCSSProperty_border_y_spacing:
-  case eCSSProperty_play_during_flags:
-  case eCSSProperty_play_during_uri:
-  case eCSSProperty_size_height:
-  case eCSSProperty_size_width:
   case eCSSProperty_margin_end_value:
   case eCSSProperty_margin_left_value:
   case eCSSProperty_margin_right_value:
@@ -4179,12 +4183,6 @@ PRBool CSSParserImpl::ParseSingleValueProperty(nsresult& aErrorCode,
     NS_ERROR("not a single value property");
     return PR_FALSE;
 
-  case eCSSProperty_border_x_spacing:
-  case eCSSProperty_border_y_spacing:
-  case eCSSProperty_play_during_flags:
-  case eCSSProperty_play_during_uri:
-  case eCSSProperty_size_height:
-  case eCSSProperty_size_width:
   case eCSSProperty_margin_left_ltr_source:
   case eCSSProperty_margin_left_rtl_source:
   case eCSSProperty_margin_right_ltr_source:
@@ -4874,8 +4872,9 @@ PRBool CSSParserImpl::ParseBorderSpacing(nsresult& aErrorCode)
       if (ParsePositiveVariant(aErrorCode, yValue, VARIANT_LENGTH, nsnull)) {
         // We have two numbers
         if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-          AppendValue(eCSSProperty_border_x_spacing, xValue);
-          AppendValue(eCSSProperty_border_y_spacing, yValue);
+          mTempData.mTable.mBorderSpacing.mXValue = xValue;
+          mTempData.mTable.mBorderSpacing.mYValue = yValue;
+          mTempData.SetPropertyBit(eCSSProperty_border_spacing);
           return PR_TRUE;
         }
         return PR_FALSE;
@@ -4885,8 +4884,8 @@ PRBool CSSParserImpl::ParseBorderSpacing(nsresult& aErrorCode)
     // We have one length which is the horizontal spacing. Create a value for
     // the vertical spacing which is equal
     if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-      AppendValue(eCSSProperty_border_x_spacing, xValue);
-      AppendValue(eCSSProperty_border_y_spacing, xValue);
+      mTempData.mTable.mBorderSpacing.SetBothValuesTo(xValue);
+      mTempData.SetPropertyBit(eCSSProperty_border_spacing);
       return PR_TRUE;
     }
   }
@@ -5649,8 +5648,9 @@ PRBool CSSParserImpl::ParsePlayDuring(nsresult& aErrorCode)
       }
     }
     if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-      AppendValue(eCSSProperty_play_during_uri, playDuring);
-      AppendValue(eCSSProperty_play_during_flags, flags);
+      mTempData.mAural.mPlayDuring.mXValue = playDuring;
+      mTempData.mAural.mPlayDuring.mYValue = flags;
+      mTempData.SetPropertyBit(eCSSProperty_play_during);
       return PR_TRUE;
     }
   }
@@ -5713,16 +5713,17 @@ PRBool CSSParserImpl::ParseSize(nsresult& aErrorCode)
       nsCSSValue  height;
       if (ParseVariant(aErrorCode, height, VARIANT_LENGTH, nsnull)) {
         if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-          AppendValue(eCSSProperty_size_width, width);
-          AppendValue(eCSSProperty_size_height, height);
+          mTempData.mPage.mSize.mXValue = width;
+          mTempData.mPage.mSize.mYValue = height;
+          mTempData.SetPropertyBit(eCSSProperty_size);
           return PR_TRUE;
         }
         return PR_FALSE;
       }
     }
     if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-      AppendValue(eCSSProperty_size_width, width);
-      AppendValue(eCSSProperty_size_height, width);
+      mTempData.mPage.mSize.SetBothValuesTo(width);
+      mTempData.SetPropertyBit(eCSSProperty_size);
       return PR_TRUE;
     }
   }
diff --git a/content/html/style/src/nsCSSStruct.cpp b/content/html/style/src/nsCSSStruct.cpp
index a4cac3eaa957..c6d5b3f6a3b6 100644
--- a/content/html/style/src/nsCSSStruct.cpp
+++ b/content/html/style/src/nsCSSStruct.cpp
@@ -49,6 +49,8 @@
 #include "nsStyleConsts.h"
 
 #include "nsCOMPtr.h"
+#include "nsReadableUtils.h"
+#include "nsPrintfCString.h"
 
 #define CSS_IF_DELETE(ptr)  if (nsnull != ptr)  { delete ptr; ptr = nsnull; }
 
@@ -382,6 +384,25 @@ void nsCSSRect::List(FILE* out, PRInt32 aIndent, const nsCSSProperty aTRBL[]) co
 }
 #endif
 
+// --- nsCSSValuePair -------------------
+#ifdef DEBUG
+void nsCSSValuePair::AppendToString(nsAString& aString,
+                                    nsCSSProperty aPropName) const
+{
+  if (mXValue.GetUnit() != eCSSUnit_Null) {
+    AppendUTF8toUTF16(nsCSSProps::GetStringValue(aPropName), aString);
+    aString.Append(NS_LITERAL_STRING(": "));
+    mXValue.AppendToString(aString);
+    NS_ASSERTION(mYValue.GetUnit() != eCSSUnit_Null,
+                 nsPrintfCString("Parsed half of a %s?",
+                                 nsCSSProps::GetStringValue(aPropName).get()).get());
+    aString.Append(PRUnichar(' '));
+    mYValue.AppendToString(aString);
+  }
+}
+#endif
+
+
 // --- nsCSSValueListRect -----------------
 
 MOZ_DECL_CTOR_COUNTER(nsCSSValueListRect)
@@ -738,8 +759,7 @@ nsCSSTable::nsCSSTable(void)
 
 nsCSSTable::nsCSSTable(const nsCSSTable& aCopy)
   : mBorderCollapse(aCopy.mBorderCollapse),
-    mBorderSpacingX(aCopy.mBorderSpacingX),
-    mBorderSpacingY(aCopy.mBorderSpacingY),
+    mBorderSpacing(aCopy.mBorderSpacing),
     mCaptionSide(aCopy.mCaptionSide),
     mEmptyCells(aCopy.mEmptyCells),
     mLayout(aCopy.mLayout)
@@ -760,8 +780,7 @@ void nsCSSTable::List(FILE* out, PRInt32 aIndent) const
   nsAutoString buffer;
 
   mBorderCollapse.AppendToString(buffer, eCSSProperty_border_collapse);
-  mBorderSpacingX.AppendToString(buffer, eCSSProperty_border_x_spacing);
-  mBorderSpacingY.AppendToString(buffer, eCSSProperty_border_y_spacing);
+  mBorderSpacing.AppendToString(buffer, eCSSProperty_border_spacing);
   mCaptionSide.AppendToString(buffer, eCSSProperty_caption_side);
   mEmptyCells.AppendToString(buffer, eCSSProperty_empty_cells);
   mLayout.AppendToString(buffer, eCSSProperty_table_layout);
@@ -822,8 +841,7 @@ nsCSSPage::nsCSSPage(void)
 
 nsCSSPage::nsCSSPage(const nsCSSPage& aCopy)
   : mMarks(aCopy.mMarks),
-    mSizeWidth(aCopy.mSizeWidth),
-    mSizeHeight(aCopy.mSizeHeight)
+    mSize(aCopy.mSize)
 {
   MOZ_COUNT_CTOR(nsCSSPage);
 }
@@ -841,8 +859,7 @@ void nsCSSPage::List(FILE* out, PRInt32 aIndent) const
   nsAutoString buffer;
 
   mMarks.AppendToString(buffer, eCSSProperty_marks);
-  mSizeWidth.AppendToString(buffer, eCSSProperty_size_width);
-  mSizeHeight.AppendToString(buffer, eCSSProperty_size_height);
+  mSize.AppendToString(buffer, eCSSProperty_size);
 
   fputs(NS_LossyConvertUCS2toASCII(buffer).get(), out);
 }
@@ -1068,7 +1085,6 @@ nsCSSAural::nsCSSAural(const nsCSSAural& aCopy)
     mPitch(aCopy.mPitch),
     mPitchRange(aCopy.mPitchRange),
     mPlayDuring(aCopy.mPlayDuring),
-    mPlayDuringFlags(aCopy.mPlayDuringFlags),
     mRichness(aCopy.mRichness),
     mSpeak(aCopy.mSpeak),
     mSpeakHeader(aCopy.mSpeakHeader),
@@ -1102,8 +1118,7 @@ void nsCSSAural::List(FILE* out, PRInt32 aIndent) const
   mPauseBefore.AppendToString(buffer, eCSSProperty_pause_before);
   mPitch.AppendToString(buffer, eCSSProperty_pitch);
   mPitchRange.AppendToString(buffer, eCSSProperty_pitch_range);
-  mPlayDuring.AppendToString(buffer, eCSSProperty_play_during_uri);
-  mPlayDuringFlags.AppendToString(buffer, eCSSProperty_play_during_flags);
+  mPlayDuring.AppendToString(buffer, eCSSProperty_play_during);
   mRichness.AppendToString(buffer, eCSSProperty_richness);
   mSpeak.AppendToString(buffer, eCSSProperty_speak);
   mSpeakHeader.AppendToString(buffer, eCSSProperty_speak_header);
diff --git a/content/html/style/src/nsCSSStruct.h b/content/html/style/src/nsCSSStruct.h
index ae641fcff599..69c1dee785a4 100644
--- a/content/html/style/src/nsCSSStruct.h
+++ b/content/html/style/src/nsCSSStruct.h
@@ -199,6 +199,47 @@ struct nsCSSRect {
   static const side_type sides[4];
 };
 
+MOZ_DECL_CTOR_COUNTER(nsCSSValuePair)
+
+struct nsCSSValuePair {
+  nsCSSValuePair()
+  {
+    MOZ_COUNT_CTOR(nsCSSValuePair);
+  }
+  nsCSSValuePair(const nsCSSValuePair& aCopy)
+    : mXValue(aCopy.mXValue),
+      mYValue(aCopy.mYValue)
+  { 
+    MOZ_COUNT_CTOR(nsCSSValuePair);
+  }
+  ~nsCSSValuePair()
+  {
+    MOZ_COUNT_DTOR(nsCSSValuePair);
+  }
+
+  PRBool operator==(const nsCSSValuePair& aOther) const {
+    return mXValue == aOther.mXValue &&
+           mYValue == aOther.mYValue;
+  }
+
+  PRBool operator!=(const nsCSSValuePair& aOther) const {
+    return mXValue != aOther.mXValue ||
+           mYValue != aOther.mYValue;
+  }
+
+  void SetBothValuesTo(const nsCSSValue& aValue) {
+    mXValue = aValue;
+    mYValue = aValue;
+  }
+
+#ifdef DEBUG
+  void AppendToString(nsAString& aString, nsCSSProperty aPropName) const;
+#endif
+  
+  nsCSSValue mXValue;
+  nsCSSValue mYValue;
+};
+
 struct nsCSSValueListRect {
   nsCSSValueListRect(void);
   nsCSSValueListRect(const nsCSSValueListRect& aCopy);
@@ -338,8 +379,7 @@ struct nsCSSTable : public nsCSSStruct  { // NEW
 #endif
 
   nsCSSValue mBorderCollapse;
-  nsCSSValue mBorderSpacingX;
-  nsCSSValue mBorderSpacingY;
+  nsCSSValuePair mBorderSpacing;
   nsCSSValue mCaptionSide;
   nsCSSValue mEmptyCells;
   
@@ -384,8 +424,7 @@ struct nsCSSPage : public nsCSSStruct  { // NEW
 #endif
 
   nsCSSValue mMarks;
-  nsCSSValue mSizeWidth;
-  nsCSSValue mSizeHeight;
+  nsCSSValuePair mSize;
 };
 
 struct nsRuleDataPage : public nsCSSPage {
@@ -473,8 +512,7 @@ struct nsCSSAural : public nsCSSStruct  { // NEW
   nsCSSValue mPauseBefore;
   nsCSSValue mPitch;
   nsCSSValue mPitchRange;
-  nsCSSValue mPlayDuring;
-  nsCSSValue mPlayDuringFlags;
+  nsCSSValuePair mPlayDuring; // mXValue is URI, mYValue are flags
   nsCSSValue mRichness;
   nsCSSValue mSpeak;
   nsCSSValue mSpeakHeader;
diff --git a/content/html/style/src/nsComputedDOMStyle.cpp b/content/html/style/src/nsComputedDOMStyle.cpp
index dbdd5b85c352..4be1af210cd0 100644
--- a/content/html/style/src/nsComputedDOMStyle.cpp
+++ b/content/html/style/src/nsComputedDOMStyle.cpp
@@ -972,7 +972,41 @@ nsresult
 nsComputedDOMStyle::GetBorderSpacing(nsIFrame *aFrame,
                                      nsIDOMCSSValue** aValue)
 {
-  return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
+  nsDOMCSSValueList *valueList = GetROCSSValueList(PR_FALSE);
+  NS_ENSURE_TRUE(valueList, NS_ERROR_OUT_OF_MEMORY);
+
+  const nsStyleTableBorder *border = nsnull;
+  GetStyleData(eStyleStruct_TableBorder, (const nsStyleStruct*&)border, aFrame);
+  if (border) {
+    nsROCSSPrimitiveValue* xSpacing = GetROCSSPrimitiveValue();
+    if (!xSpacing) {
+      delete valueList;
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    if (!valueList->AppendCSSValue(xSpacing)) {
+      delete valueList;
+      delete xSpacing;
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    
+    nsROCSSPrimitiveValue* ySpacing = GetROCSSPrimitiveValue();
+    if (!ySpacing) {
+      delete valueList;
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    if (!valueList->AppendCSSValue(ySpacing)) {
+      delete valueList;
+      delete ySpacing;
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    // border-spacing will always be a coord
+    xSpacing->SetTwips(border->mBorderSpacingX.GetCoordValue());
+    ySpacing->SetTwips(border->mBorderSpacingY.GetCoordValue());
+        
+  }
+
+  return CallQueryInterface(valueList, aValue);
 }
 
 nsresult
@@ -3522,7 +3556,7 @@ nsComputedDOMStyle::GetQueryablePropertyMap(PRUint32* aLength)
     COMPUTED_STYLE_MAP_ENTRY(border_right_color,            BorderRightColor),
     COMPUTED_STYLE_MAP_ENTRY(border_right_style,            BorderRightStyle),
     COMPUTED_STYLE_MAP_ENTRY(border_right_width,            BorderRightWidth),
-    //// COMPUTED_STYLE_MAP_ENTRY(border_spacing,           BorderSpacing),
+    COMPUTED_STYLE_MAP_ENTRY(border_spacing,                BorderSpacing),
     //// COMPUTED_STYLE_MAP_ENTRY(border_style,             BorderStyle),
     //// COMPUTED_STYLE_MAP_ENTRY(border_top,               BorderTop),
     COMPUTED_STYLE_MAP_ENTRY(border_top_color,              BorderTopColor),
diff --git a/content/shared/public/nsCSSPropList.h b/content/shared/public/nsCSSPropList.h
index bdab54964bd0..383b027862a7 100644
--- a/content/shared/public/nsCSSPropList.h
+++ b/content/shared/public/nsCSSPropList.h
@@ -312,7 +312,7 @@ CSS_PROP_BORDER(border-right-color, border_right_color, BorderRightColor, Margin
 CSS_PROP_BORDER(-moz-border-right-colors, border_right_colors, MozBorderRightColors, Margin, mBorderColors.mRight, eCSSType_ValueList, PR_FALSE, nsnull)
 CSS_PROP_BORDER(border-right-style, border_right_style, BorderRightStyle, Margin, mBorderStyle.mRight, eCSSType_Value, PR_FALSE, kBorderStyleKTable)  // on/off will need reflow
 CSS_PROP_BORDER(border-right-width, border_right_width, BorderRightWidth, Margin, mBorderWidth.mRight, eCSSType_Value, PR_FALSE, kBorderWidthKTable)
-CSS_PROP_SHORTHAND(border-spacing, border_spacing, BorderSpacing)
+CSS_PROP_TABLEBORDER(border-spacing, border_spacing, BorderSpacing, Table, mBorderSpacing, eCSSType_ValuePair, PR_FALSE, nsnull) // XXX bug 3935
 CSS_PROP_SHORTHAND(border-style, border_style, BorderStyle)  // on/off will need reflow
 CSS_PROP_SHORTHAND(border-top, border_top, BorderTop)
 CSS_PROP_BORDER(border-top-color, border_top_color, BorderTopColor, Margin, mBorderColor.mTop, eCSSType_Value, PR_FALSE, kBorderColorKTable)
@@ -320,10 +320,6 @@ CSS_PROP_BORDER(-moz-border-top-colors, border_top_colors, MozBorderTopColors, M
 CSS_PROP_BORDER(border-top-style, border_top_style, BorderTopStyle, Margin, mBorderStyle.mTop, eCSSType_Value, PR_FALSE, kBorderStyleKTable)  // on/off will need reflow
 CSS_PROP_BORDER(border-top-width, border_top_width, BorderTopWidth, Margin, mBorderWidth.mTop, eCSSType_Value, PR_FALSE, kBorderWidthKTable)
 CSS_PROP_SHORTHAND(border-width, border_width, BorderWidth)
-#ifndef CSS_PROP_LIST_EXCLUDE_INTERNAL
-CSS_PROP_TABLEBORDER(-x-border-x-spacing, border_x_spacing, BorderXSpacing, Table, mBorderSpacingX, eCSSType_Value, PR_FALSE, nsnull) // XXX bug 3935
-CSS_PROP_TABLEBORDER(-x-border-y-spacing, border_y_spacing, BorderYSpacing, Table, mBorderSpacingY, eCSSType_Value, PR_FALSE, nsnull) // XXX bug 3935
-#endif /* !defined (CSS_PROP_LIST_EXCLUDE_INTERNAL) */
 CSS_PROP_POSITION(bottom, bottom, Bottom, Position, mOffset.mBottom, eCSSType_Value, PR_TRUE, nsnull)
 CSS_PROP_POSITION(-moz-box-sizing, box_sizing, MozBoxSizing, Position, mBoxSizing, eCSSType_Value, PR_FALSE, kBoxSizingKTable) // XXX bug 3935
 CSS_PROP_TABLEBORDER(caption-side, caption_side, CaptionSide, Table, mCaptionSide, eCSSType_Value, PR_FALSE, kCaptionSideKTable)
@@ -441,20 +437,12 @@ CSS_PROP_BACKENDONLY(pause-after, pause_after, PauseAfter, Aural, mPauseAfter, e
 CSS_PROP_BACKENDONLY(pause-before, pause_before, PauseBefore, Aural, mPauseBefore, eCSSType_Value, PR_FALSE, nsnull)
 CSS_PROP_BACKENDONLY(pitch, pitch, Pitch, Aural, mPitch, eCSSType_Value, PR_FALSE, kPitchKTable)
 CSS_PROP_BACKENDONLY(pitch-range, pitch_range, PitchRange, Aural, mPitchRange, eCSSType_Value, PR_FALSE, nsnull)
-CSS_PROP_SHORTHAND(play-during, play_during, PlayDuring)
-#ifndef CSS_PROP_LIST_EXCLUDE_INTERNAL
-CSS_PROP_BACKENDONLY(-x-play-during-flags, play_during_flags, PlayDuringFlags, Aural, mPlayDuringFlags, eCSSType_Value, PR_FALSE, kPlayDuringKTable) // XXX why is this here?
-CSS_PROP_BACKENDONLY(-x-play-during-uri, play_during_uri, PlayDuringURI, Aural, mPlayDuring, eCSSType_Value, PR_FALSE, nsnull) // XXX why is this here?
-#endif /* !defined (CSS_PROP_LIST_EXCLUDE_INTERNAL) */
+CSS_PROP_BACKENDONLY(play-during, play_during, PlayDuring, Aural, mPlayDuring, eCSSType_ValuePair, PR_FALSE, kPlayDuringKTable)
 CSS_PROP_DISPLAY(position, position, Position, Display, mPosition, eCSSType_Value, PR_FALSE, kPositionKTable)
 CSS_PROP_QUOTES(quotes, quotes, Quotes, Content, mQuotes, eCSSType_Quotes, PR_FALSE, nsnull)
 CSS_PROP_BACKENDONLY(richness, richness, Richness, Aural, mRichness, eCSSType_Value, PR_FALSE, nsnull)
 CSS_PROP_POSITION(right, right, Right, Position, mOffset.mRight, eCSSType_Value, PR_TRUE, nsnull)
-CSS_PROP_SHORTHAND(size, size, Size)
-#ifndef CSS_PROP_LIST_EXCLUDE_INTERNAL
-CSS_PROP_BACKENDONLY(-x-size-height, size_height, SizeHeight, Page, mSizeHeight, eCSSType_Value, PR_FALSE, kPageSizeKTable) // XXX bug 3935
-CSS_PROP_BACKENDONLY(-x-size-width, size_width, SizeWidth, Page, mSizeWidth, eCSSType_Value, PR_FALSE, kPageSizeKTable) // XXX bug 3935
-#endif /* !defined (CSS_PROP_LIST_EXCLUDE_INTERNAL) */
+CSS_PROP_BACKENDONLY(size, size, Size, Page, mSize, eCSSType_ValuePair, PR_FALSE, kPageSizeKTable)
 CSS_PROP_BACKENDONLY(speak, speak, Speak, Aural, mSpeak, eCSSType_Value, PR_FALSE, kSpeakKTable)
 CSS_PROP_BACKENDONLY(speak-header, speak_header, SpeakHeader, Aural, mSpeakHeader, eCSSType_Value, PR_FALSE, kSpeakHeaderKTable)
 CSS_PROP_BACKENDONLY(speak-numeral, speak_numeral, SpeakNumeral, Aural, mSpeakNumeral, eCSSType_Value, PR_FALSE, kSpeakNumeralKTable)
diff --git a/content/shared/public/nsCSSProperty.h b/content/shared/public/nsCSSProperty.h
index 2f807a8339c5..128a08258611 100644
--- a/content/shared/public/nsCSSProperty.h
+++ b/content/shared/public/nsCSSProperty.h
@@ -67,6 +67,7 @@ enum nsCSSProperty {
 enum nsCSSType {
   eCSSType_Value,
   eCSSType_Rect,
+  eCSSType_ValuePair,
   eCSSType_ValueList,
   eCSSType_CounterData,
   eCSSType_Quotes,
diff --git a/content/shared/src/nsCSSProps.cpp b/content/shared/src/nsCSSProps.cpp
index bc1449bcb383..18f499fc901b 100644
--- a/content/shared/src/nsCSSProps.cpp
+++ b/content/shared/src/nsCSSProps.cpp
@@ -1215,12 +1215,6 @@ static const nsCSSProperty gBorderRightSubpropTable[] = {
   eCSSProperty_UNKNOWN
 };
 
-static const nsCSSProperty gBorderSpacingSubpropTable[] = {
-  eCSSProperty_border_x_spacing,
-  eCSSProperty_border_y_spacing,
-  eCSSProperty_UNKNOWN
-};
-
 static const nsCSSProperty gBorderStyleSubpropTable[] = {
   // Code relies on these being in top-right-bottom-left order.
   eCSSProperty_border_top_style,
@@ -1385,18 +1379,6 @@ static const nsCSSProperty gPauseSubpropTable[] = {
   eCSSProperty_UNKNOWN
 };
 
-static const nsCSSProperty gPlayDuringSubpropTable[] = {
-  eCSSProperty_play_during_uri,
-  eCSSProperty_play_during_flags,
-  eCSSProperty_UNKNOWN
-};
-
-static const nsCSSProperty gSizeSubpropTable[] = {
-  eCSSProperty_size_width,
-  eCSSProperty_size_height,
-  eCSSProperty_UNKNOWN
-};
-
 const nsCSSProperty *const
 nsCSSProps::kSubpropertyTable[eCSSProperty_COUNT - eCSSProperty_COUNT_no_shorthands] = {
     #define CSS_PROP_SHORTHAND(name_, id_, method_) g##method_##SubpropTable,
diff --git a/layout/style/nsCSSDataBlock.cpp b/layout/style/nsCSSDataBlock.cpp
index c54e613855cb..d33701220938 100644
--- a/layout/style/nsCSSDataBlock.cpp
+++ b/layout/style/nsCSSDataBlock.cpp
@@ -1,3 +1,4 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
 /* ***** BEGIN LICENSE BLOCK *****
  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
  *
@@ -66,6 +67,11 @@ struct CDBRectStorage {
 
 };
 
+struct CDBValuePairStorage {
+    nsCSSProperty property;
+    nsCSSValuePair value;
+};
+
 struct CDBPointerStorage {
     nsCSSProperty property;
     void *value;
@@ -74,6 +80,7 @@ struct CDBPointerStorage {
 enum {
     CDBValueStorage_advance = sizeof(CDBValueStorage),
     CDBRectStorage_advance = sizeof(CDBRectStorage),
+    CDBValuePairStorage_advance = sizeof(CDBValuePairStorage),
     // round up using the closest estimate we can get of the alignment
     // requirements of nsCSSValue:
     CDBPointerStorage_advance = PR_ROUNDUP(sizeof(CDBPointerStorage),
@@ -112,6 +119,14 @@ inline const nsCSSRect* RectAtCursor(const char *aCursor) {
     return & NS_REINTERPRET_CAST(const CDBRectStorage*, aCursor)->value;
 }
 
+inline nsCSSValuePair* ValuePairAtCursor(char *aCursor) {
+  return & NS_REINTERPRET_CAST(CDBValuePairStorage*, aCursor)->value;
+}
+
+inline const nsCSSValuePair* ValuePairAtCursor(const char *aCursor) {
+  return & NS_REINTERPRET_CAST(const CDBValuePairStorage*, aCursor)->value;
+}
+
 inline void*& PointerAtCursor(char *aCursor) {
     return NS_REINTERPRET_CAST(CDBPointerStorage*, aCursor)->value;
 }
@@ -215,6 +230,18 @@ nsCSSCompressedDataBlock::MapRuleInfoInto(nsRuleData *aRuleData) const
                     cursor += CDBRectStorage_advance;
                 } break;
 
+                case eCSSType_ValuePair: {
+                    const nsCSSValuePair* val = ValuePairAtCursor(cursor);
+                    NS_ASSERTION(val->mXValue.GetUnit() != eCSSUnit_Null ||
+                                 val->mYValue.GetUnit() != eCSSUnit_Null, "oops");
+                    nsCSSValuePair* target = NS_STATIC_CAST(nsCSSValuePair*, prop);
+                    if (target->mXValue.GetUnit() == eCSSUnit_Null)
+                        target->mXValue = val->mXValue;
+                    if (target->mYValue.GetUnit() == eCSSUnit_Null)
+                        target->mYValue = val->mYValue;
+                    cursor += CDBValuePairStorage_advance;
+                } break;
+
                 case eCSSType_ValueList:
                     if (iProp == eCSSProperty_content) {
                         for (nsCSSValueList* l = ValueListAtCursor(cursor);
@@ -246,6 +273,10 @@ nsCSSCompressedDataBlock::MapRuleInfoInto(nsRuleData *aRuleData) const
                     cursor += CDBRectStorage_advance;
                 } break;
 
+                case eCSSType_ValuePair: {
+                    cursor += CDBValuePairStorage_advance;
+                } break;
+
                 case eCSSType_ValueList:
                 case eCSSType_CounterData:
                 case eCSSType_Quotes:
@@ -285,6 +316,9 @@ nsCSSCompressedDataBlock::StorageFor(nsCSSProperty aProperty) const
                 case eCSSType_Rect: {
                     return RectAtCursor(cursor);
                 }
+                case eCSSType_ValuePair: {
+                    return ValuePairAtCursor(cursor);
+                }
                 case eCSSType_ValueList:
                 case eCSSType_CounterData:
                 case eCSSType_Quotes:
@@ -302,6 +336,10 @@ nsCSSCompressedDataBlock::StorageFor(nsCSSProperty aProperty) const
                 cursor += CDBRectStorage_advance;
             } break;
 
+            case eCSSType_ValuePair: {
+                cursor += CDBValuePairStorage_advance;
+            } break;
+
             case eCSSType_ValueList:
             case eCSSType_CounterData:
             case eCSSType_Quotes:
@@ -352,6 +390,16 @@ nsCSSCompressedDataBlock::Clone() const
                 result_cursor += CDBRectStorage_advance;
             } break;
 
+            case eCSSType_ValuePair: {
+                const nsCSSValuePair* val = ValuePairAtCursor(cursor);
+                NS_ASSERTION(val->mXValue.GetUnit() != eCSSUnit_Null ||
+                             val->mYValue.GetUnit() != eCSSUnit_Null, "oops");
+                nsCSSValuePair* result_val = ValuePairAtCursor(result_cursor);
+                new (result_val) nsCSSValuePair(*val);
+                cursor += CDBValuePairStorage_advance;
+                result_cursor += CDBValuePairStorage_advance;
+            } break;
+
             case eCSSType_ValueList:
             case eCSSType_CounterData:
             case eCSSType_Quotes:
@@ -421,6 +469,14 @@ nsCSSCompressedDataBlock::Destroy()
                 cursor += CDBRectStorage_advance;
             } break;
 
+            case eCSSType_ValuePair: {
+                const nsCSSValuePair* val = ValuePairAtCursor(cursor);
+                NS_ASSERTION(val->mXValue.GetUnit() != eCSSUnit_Null ||
+                             val->mYValue.GetUnit() != eCSSUnit_Null, "oops");
+                val->~nsCSSValuePair();
+                cursor += CDBValuePairStorage_advance;
+            } break;
+
             case eCSSType_ValueList: {
                 nsCSSValueList* val = ValueListAtCursor(cursor);
                 NS_ASSERTION(val, "oops");
@@ -532,6 +588,14 @@ nsCSSExpandedDataBlock::DoExpand(nsCSSCompressedDataBlock *aBlock,
                 cursor += CDBRectStorage_advance;
             } break;
 
+            case eCSSType_ValuePair: {
+                const nsCSSValuePair* val = ValuePairAtCursor(cursor);
+                NS_ASSERTION(val->mXValue.GetUnit() != eCSSUnit_Null ||
+                             val->mYValue.GetUnit() != eCSSUnit_Null, "oops");
+                memcpy(prop, val, sizeof(nsCSSValuePair));
+                cursor += CDBValuePairStorage_advance;
+            } break;
+
             case eCSSType_ValueList:
             case eCSSType_CounterData:
             case eCSSType_Quotes:
@@ -594,6 +658,14 @@ nsCSSExpandedDataBlock::ComputeSize()
                     }
                 } break;
 
+                case eCSSType_ValuePair: {
+                    nsCSSValuePair* val = NS_STATIC_CAST(nsCSSValuePair*, prop);
+                    if (val->mXValue.GetUnit() != eCSSUnit_Null ||
+                        val->mYValue.GetUnit() != eCSSUnit_Null) {
+                        increment = CDBValuePairStorage_advance;
+                    }
+                } break;
+
                 case eCSSType_ValueList:
                 case eCSSType_CounterData:
                 case eCSSType_Quotes:
@@ -692,6 +764,20 @@ nsCSSExpandedDataBlock::Compress(nsCSSCompressedDataBlock **aNormalBlock,
                     }
                 } break;
 
+                case eCSSType_ValuePair: {
+                    nsCSSValuePair* val = NS_STATIC_CAST(nsCSSValuePair*, prop);
+                    if (val->mXValue.GetUnit() != eCSSUnit_Null ||
+                        val->mYValue.GetUnit() != eCSSUnit_Null) {
+                        CDBValuePairStorage *storage =
+                            NS_REINTERPRET_CAST(CDBValuePairStorage*, cursor);
+                        storage->property = iProp;
+                        memcpy(&storage->value, val, sizeof(nsCSSValuePair));
+                        new (val) nsCSSValuePair();
+                        cursor += CDBValuePairStorage_advance;
+                        present = PR_TRUE;
+                    }
+                } break;
+
                 case eCSSType_ValueList:
                 case eCSSType_CounterData:
                 case eCSSType_Quotes:
@@ -769,6 +855,12 @@ nsCSSExpandedDataBlock::ClearProperty(nsCSSProperty aPropID)
             val->Reset();
         } break;
 
+        case eCSSType_ValuePair: {
+            nsCSSValuePair* val = NS_STATIC_CAST(nsCSSValuePair*, prop);
+            val->mXValue.Reset();
+            val->mYValue.Reset();
+        } break;
+
         case eCSSType_ValueList: {
             nsCSSValueList*& val = *NS_STATIC_CAST(nsCSSValueList**, prop);
             if (val) {
@@ -837,6 +929,14 @@ nsCSSExpandedDataBlock::DoAssertInitialState()
                              "not initial state");
             } break;
 
+            case eCSSType_ValuePair: {
+                nsCSSValuePair* val = NS_STATIC_CAST(nsCSSValuePair*, prop);
+                NS_ASSERTION(val->mXValue.GetUnit() == eCSSUnit_Null,
+                             "not initial state");
+                NS_ASSERTION(val->mYValue.GetUnit() == eCSSUnit_Null,
+                             "not initial state");
+            } break;
+
             case eCSSType_ValueList: {
                 nsCSSValueList* val = *NS_STATIC_CAST(nsCSSValueList**, prop);
                 NS_ASSERTION(val == nsnull, "not initial state");
diff --git a/layout/style/nsCSSDeclaration.cpp b/layout/style/nsCSSDeclaration.cpp
index 46a5b2eec2b3..671b7c3c3489 100644
--- a/layout/style/nsCSSDeclaration.cpp
+++ b/layout/style/nsCSSDeclaration.cpp
@@ -40,6 +40,7 @@
 #include "nsString.h"
 #include "nsIAtom.h"
 #include "nsUnicharUtils.h"
+#include "nsReadableUtils.h"
 #include "nsCRT.h"
 #include "nsCSSProps.h"
 #include "nsUnitConversion.h"
@@ -214,6 +215,15 @@ PRBool nsCSSDeclaration::AppendValueToString(nsCSSProperty aProperty, nsAString&
           aResult.Append(PRUnichar(')'));
         }
       } break;
+      case eCSSType_ValuePair: {
+        const nsCSSValuePair *pair = NS_STATIC_CAST(const nsCSSValuePair*, storage);
+        AppendCSSValueToString(aProperty, pair->mXValue, aResult);
+        if (pair->mYValue != pair->mXValue) {
+          // Only output a Y value if it's different from the X value
+          aResult.Append(PRUnichar(' '));
+          AppendCSSValueToString(aProperty, pair->mYValue, aResult);
+        }
+      } break;
       case eCSSType_ValueList: {
         const nsCSSValueList* val =
             *NS_STATIC_CAST(nsCSSValueList*const*, storage);
@@ -364,18 +374,6 @@ PRBool nsCSSDeclaration::AppendCSSValueToString(nsCSSProperty aProperty, const n
         AppendASCIItoUTF16(nsCSSProps::LookupPropertyValue(aProperty, NS_STYLE_AZIMUTH_BEHIND), aResult);
       }
     }
-    else if (eCSSProperty_play_during_flags == aProperty) {
-      PRInt32 intValue = aValue.GetIntValue();
-      if ((NS_STYLE_PLAY_DURING_MIX & intValue) != 0) {
-        AppendASCIItoUTF16(nsCSSProps::LookupPropertyValue(aProperty, NS_STYLE_PLAY_DURING_MIX), aResult);
-      }
-      if ((NS_STYLE_PLAY_DURING_REPEAT & intValue) != 0) {
-        if (NS_STYLE_PLAY_DURING_REPEAT != intValue) {
-          aResult.Append(PRUnichar(' '));
-        }
-        AppendASCIItoUTF16(nsCSSProps::LookupPropertyValue(aProperty, NS_STYLE_PLAY_DURING_REPEAT), aResult);
-      }
-    }
     else if (eCSSProperty_marks == aProperty) {
       PRInt32 intValue = aValue.GetIntValue();
       if ((NS_STYLE_PAGE_MARKS_CROP & intValue) != 0) {
@@ -493,7 +491,9 @@ nsCSSDeclaration::GetValue(nsCSSProperty aProperty,
   aValue.Truncate(0);
 
   // simple properties are easy.
-  if (!nsCSSProps::IsShorthand(aProperty)) {
+  if (!nsCSSProps::IsShorthand(aProperty) &&
+      // play-during is not a real shorthand, but is special...
+      aProperty != eCSSProperty_play_during) {
     AppendValueToString(aProperty, aValue);
     return NS_OK;
   }
@@ -584,16 +584,6 @@ nsCSSDeclaration::GetValue(nsCSSProperty aProperty,
       }
       break;
     }
-    case eCSSProperty_border_spacing:
-      if (AppendValueToString(eCSSProperty_border_x_spacing, aValue)) {
-        aValue.Append(PRUnichar(' '));
-#ifdef DEBUG
-        PRBool check =
-#endif
-          AppendValueToString(eCSSProperty_border_y_spacing, aValue);
-        NS_ASSERTION(check, "we parsed half of border-spacing");
-      }
-      break;
     case eCSSProperty_cue: {
       if (AppendValueToString(eCSSProperty_cue_after, aValue)) {
         aValue.Append(PRUnichar(' '));
@@ -646,14 +636,6 @@ nsCSSDeclaration::GetValue(nsCSSProperty aProperty,
       }
       break;
     }
-    case eCSSProperty_size: {
-      if (AppendValueToString(eCSSProperty_size_width, aValue)) {
-        aValue.Append(PRUnichar(' '));
-        if (!AppendValueToString(eCSSProperty_size_height, aValue))
-          aValue.Truncate();
-      }
-      break;
-    }
     case eCSSProperty_background_position: {
       if (AppendValueToString(eCSSProperty_background_x_position, aValue)) {
         aValue.Append(PRUnichar(' '));
@@ -666,11 +648,32 @@ nsCSSDeclaration::GetValue(nsCSSProperty aProperty,
       break;
     }
     case eCSSProperty_play_during: {
-      if (AppendValueToString(eCSSProperty_play_during_uri, aValue)) {
-        nsAutoString tmp;
-        if (AppendValueToString(eCSSProperty_play_during_flags, tmp)) {
-          aValue.Append(PRUnichar(' '));
-          aValue.Append(tmp);
+      nsCSSCompressedDataBlock *data =
+        GetValueIsImportant(eCSSProperty_play_during) ? mImportantData : mData;
+      const void *storage = data->StorageFor(eCSSProperty_play_during);
+      if (!storage) {
+        break;
+      }
+      NS_ASSERTION(nsCSSProps::kTypeTable[eCSSProperty_play_during] ==
+                   eCSSType_ValuePair,
+                   "Someone changed the storage type of play-during!");
+      const nsCSSValuePair *pair = NS_STATIC_CAST(const nsCSSValuePair*, storage);
+      AppendCSSValueToString(aProperty, pair->mXValue, aValue);
+      if (pair->mYValue != eCSSUnit_Null) {
+        aValue.Append(PRUnichar(' '));
+        PRInt32 intValue = pair->mYValue.GetIntValue();
+        if ((NS_STYLE_PLAY_DURING_MIX & intValue) != 0) {
+          AppendUTF8toUTF16(nsCSSProps::LookupPropertyValue(aProperty,
+                                                     NS_STYLE_PLAY_DURING_MIX),
+                            aValue);
+        }
+        if ((NS_STYLE_PLAY_DURING_REPEAT & intValue) != 0) {
+          if (NS_STYLE_PLAY_DURING_REPEAT != intValue) {
+            aValue.Append(PRUnichar(' '));
+          }
+          AppendUTF8toUTF16(nsCSSProps::LookupPropertyValue(aProperty,
+                                                  NS_STYLE_PLAY_DURING_REPEAT),
+                            aValue);
         }
       }
       break;
diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index 4f39655dab6d..fd4e766ee153 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -3223,6 +3223,16 @@ CSSParserImpl::DoTransferTempData(nsCSSDeclaration* aDeclaration,
       new (source) nsCSSRect();
     } break;
 
+    case eCSSType_ValuePair: {
+      nsCSSValuePair *source = NS_STATIC_CAST(nsCSSValuePair*, v_source);
+      nsCSSValuePair *dest = NS_STATIC_CAST(nsCSSValuePair*, v_dest);
+      if (*source != *dest)
+        *aChanged = PR_TRUE;
+      dest->~nsCSSValuePair();
+      memcpy(dest, source, sizeof(nsCSSValuePair));
+      new (source) nsCSSValuePair();
+    } break;
+
     case eCSSType_ValueList: {
       nsCSSValueList **source = NS_STATIC_CAST(nsCSSValueList**, v_source);
       nsCSSValueList **dest = NS_STATIC_CAST(nsCSSValueList**, v_dest);
@@ -4060,12 +4070,6 @@ PRBool CSSParserImpl::ParseProperty(nsresult& aErrorCode,
   // by compound property parsing routines (e.g. "background-position").
   case eCSSProperty_background_x_position:
   case eCSSProperty_background_y_position:
-  case eCSSProperty_border_x_spacing:
-  case eCSSProperty_border_y_spacing:
-  case eCSSProperty_play_during_flags:
-  case eCSSProperty_play_during_uri:
-  case eCSSProperty_size_height:
-  case eCSSProperty_size_width:
   case eCSSProperty_margin_end_value:
   case eCSSProperty_margin_left_value:
   case eCSSProperty_margin_right_value:
@@ -4179,12 +4183,6 @@ PRBool CSSParserImpl::ParseSingleValueProperty(nsresult& aErrorCode,
     NS_ERROR("not a single value property");
     return PR_FALSE;
 
-  case eCSSProperty_border_x_spacing:
-  case eCSSProperty_border_y_spacing:
-  case eCSSProperty_play_during_flags:
-  case eCSSProperty_play_during_uri:
-  case eCSSProperty_size_height:
-  case eCSSProperty_size_width:
   case eCSSProperty_margin_left_ltr_source:
   case eCSSProperty_margin_left_rtl_source:
   case eCSSProperty_margin_right_ltr_source:
@@ -4874,8 +4872,9 @@ PRBool CSSParserImpl::ParseBorderSpacing(nsresult& aErrorCode)
       if (ParsePositiveVariant(aErrorCode, yValue, VARIANT_LENGTH, nsnull)) {
         // We have two numbers
         if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-          AppendValue(eCSSProperty_border_x_spacing, xValue);
-          AppendValue(eCSSProperty_border_y_spacing, yValue);
+          mTempData.mTable.mBorderSpacing.mXValue = xValue;
+          mTempData.mTable.mBorderSpacing.mYValue = yValue;
+          mTempData.SetPropertyBit(eCSSProperty_border_spacing);
           return PR_TRUE;
         }
         return PR_FALSE;
@@ -4885,8 +4884,8 @@ PRBool CSSParserImpl::ParseBorderSpacing(nsresult& aErrorCode)
     // We have one length which is the horizontal spacing. Create a value for
     // the vertical spacing which is equal
     if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-      AppendValue(eCSSProperty_border_x_spacing, xValue);
-      AppendValue(eCSSProperty_border_y_spacing, xValue);
+      mTempData.mTable.mBorderSpacing.SetBothValuesTo(xValue);
+      mTempData.SetPropertyBit(eCSSProperty_border_spacing);
       return PR_TRUE;
     }
   }
@@ -5649,8 +5648,9 @@ PRBool CSSParserImpl::ParsePlayDuring(nsresult& aErrorCode)
       }
     }
     if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-      AppendValue(eCSSProperty_play_during_uri, playDuring);
-      AppendValue(eCSSProperty_play_during_flags, flags);
+      mTempData.mAural.mPlayDuring.mXValue = playDuring;
+      mTempData.mAural.mPlayDuring.mYValue = flags;
+      mTempData.SetPropertyBit(eCSSProperty_play_during);
       return PR_TRUE;
     }
   }
@@ -5713,16 +5713,17 @@ PRBool CSSParserImpl::ParseSize(nsresult& aErrorCode)
       nsCSSValue  height;
       if (ParseVariant(aErrorCode, height, VARIANT_LENGTH, nsnull)) {
         if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-          AppendValue(eCSSProperty_size_width, width);
-          AppendValue(eCSSProperty_size_height, height);
+          mTempData.mPage.mSize.mXValue = width;
+          mTempData.mPage.mSize.mYValue = height;
+          mTempData.SetPropertyBit(eCSSProperty_size);
           return PR_TRUE;
         }
         return PR_FALSE;
       }
     }
     if (ExpectEndProperty(aErrorCode, PR_TRUE)) {
-      AppendValue(eCSSProperty_size_width, width);
-      AppendValue(eCSSProperty_size_height, width);
+      mTempData.mPage.mSize.SetBothValuesTo(width);
+      mTempData.SetPropertyBit(eCSSProperty_size);
       return PR_TRUE;
     }
   }
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index bdab54964bd0..383b027862a7 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -312,7 +312,7 @@ CSS_PROP_BORDER(border-right-color, border_right_color, BorderRightColor, Margin
 CSS_PROP_BORDER(-moz-border-right-colors, border_right_colors, MozBorderRightColors, Margin, mBorderColors.mRight, eCSSType_ValueList, PR_FALSE, nsnull)
 CSS_PROP_BORDER(border-right-style, border_right_style, BorderRightStyle, Margin, mBorderStyle.mRight, eCSSType_Value, PR_FALSE, kBorderStyleKTable)  // on/off will need reflow
 CSS_PROP_BORDER(border-right-width, border_right_width, BorderRightWidth, Margin, mBorderWidth.mRight, eCSSType_Value, PR_FALSE, kBorderWidthKTable)
-CSS_PROP_SHORTHAND(border-spacing, border_spacing, BorderSpacing)
+CSS_PROP_TABLEBORDER(border-spacing, border_spacing, BorderSpacing, Table, mBorderSpacing, eCSSType_ValuePair, PR_FALSE, nsnull) // XXX bug 3935
 CSS_PROP_SHORTHAND(border-style, border_style, BorderStyle)  // on/off will need reflow
 CSS_PROP_SHORTHAND(border-top, border_top, BorderTop)
 CSS_PROP_BORDER(border-top-color, border_top_color, BorderTopColor, Margin, mBorderColor.mTop, eCSSType_Value, PR_FALSE, kBorderColorKTable)
@@ -320,10 +320,6 @@ CSS_PROP_BORDER(-moz-border-top-colors, border_top_colors, MozBorderTopColors, M
 CSS_PROP_BORDER(border-top-style, border_top_style, BorderTopStyle, Margin, mBorderStyle.mTop, eCSSType_Value, PR_FALSE, kBorderStyleKTable)  // on/off will need reflow
 CSS_PROP_BORDER(border-top-width, border_top_width, BorderTopWidth, Margin, mBorderWidth.mTop, eCSSType_Value, PR_FALSE, kBorderWidthKTable)
 CSS_PROP_SHORTHAND(border-width, border_width, BorderWidth)
-#ifndef CSS_PROP_LIST_EXCLUDE_INTERNAL
-CSS_PROP_TABLEBORDER(-x-border-x-spacing, border_x_spacing, BorderXSpacing, Table, mBorderSpacingX, eCSSType_Value, PR_FALSE, nsnull) // XXX bug 3935
-CSS_PROP_TABLEBORDER(-x-border-y-spacing, border_y_spacing, BorderYSpacing, Table, mBorderSpacingY, eCSSType_Value, PR_FALSE, nsnull) // XXX bug 3935
-#endif /* !defined (CSS_PROP_LIST_EXCLUDE_INTERNAL) */
 CSS_PROP_POSITION(bottom, bottom, Bottom, Position, mOffset.mBottom, eCSSType_Value, PR_TRUE, nsnull)
 CSS_PROP_POSITION(-moz-box-sizing, box_sizing, MozBoxSizing, Position, mBoxSizing, eCSSType_Value, PR_FALSE, kBoxSizingKTable) // XXX bug 3935
 CSS_PROP_TABLEBORDER(caption-side, caption_side, CaptionSide, Table, mCaptionSide, eCSSType_Value, PR_FALSE, kCaptionSideKTable)
@@ -441,20 +437,12 @@ CSS_PROP_BACKENDONLY(pause-after, pause_after, PauseAfter, Aural, mPauseAfter, e
 CSS_PROP_BACKENDONLY(pause-before, pause_before, PauseBefore, Aural, mPauseBefore, eCSSType_Value, PR_FALSE, nsnull)
 CSS_PROP_BACKENDONLY(pitch, pitch, Pitch, Aural, mPitch, eCSSType_Value, PR_FALSE, kPitchKTable)
 CSS_PROP_BACKENDONLY(pitch-range, pitch_range, PitchRange, Aural, mPitchRange, eCSSType_Value, PR_FALSE, nsnull)
-CSS_PROP_SHORTHAND(play-during, play_during, PlayDuring)
-#ifndef CSS_PROP_LIST_EXCLUDE_INTERNAL
-CSS_PROP_BACKENDONLY(-x-play-during-flags, play_during_flags, PlayDuringFlags, Aural, mPlayDuringFlags, eCSSType_Value, PR_FALSE, kPlayDuringKTable) // XXX why is this here?
-CSS_PROP_BACKENDONLY(-x-play-during-uri, play_during_uri, PlayDuringURI, Aural, mPlayDuring, eCSSType_Value, PR_FALSE, nsnull) // XXX why is this here?
-#endif /* !defined (CSS_PROP_LIST_EXCLUDE_INTERNAL) */
+CSS_PROP_BACKENDONLY(play-during, play_during, PlayDuring, Aural, mPlayDuring, eCSSType_ValuePair, PR_FALSE, kPlayDuringKTable)
 CSS_PROP_DISPLAY(position, position, Position, Display, mPosition, eCSSType_Value, PR_FALSE, kPositionKTable)
 CSS_PROP_QUOTES(quotes, quotes, Quotes, Content, mQuotes, eCSSType_Quotes, PR_FALSE, nsnull)
 CSS_PROP_BACKENDONLY(richness, richness, Richness, Aural, mRichness, eCSSType_Value, PR_FALSE, nsnull)
 CSS_PROP_POSITION(right, right, Right, Position, mOffset.mRight, eCSSType_Value, PR_TRUE, nsnull)
-CSS_PROP_SHORTHAND(size, size, Size)
-#ifndef CSS_PROP_LIST_EXCLUDE_INTERNAL
-CSS_PROP_BACKENDONLY(-x-size-height, size_height, SizeHeight, Page, mSizeHeight, eCSSType_Value, PR_FALSE, kPageSizeKTable) // XXX bug 3935
-CSS_PROP_BACKENDONLY(-x-size-width, size_width, SizeWidth, Page, mSizeWidth, eCSSType_Value, PR_FALSE, kPageSizeKTable) // XXX bug 3935
-#endif /* !defined (CSS_PROP_LIST_EXCLUDE_INTERNAL) */
+CSS_PROP_BACKENDONLY(size, size, Size, Page, mSize, eCSSType_ValuePair, PR_FALSE, kPageSizeKTable)
 CSS_PROP_BACKENDONLY(speak, speak, Speak, Aural, mSpeak, eCSSType_Value, PR_FALSE, kSpeakKTable)
 CSS_PROP_BACKENDONLY(speak-header, speak_header, SpeakHeader, Aural, mSpeakHeader, eCSSType_Value, PR_FALSE, kSpeakHeaderKTable)
 CSS_PROP_BACKENDONLY(speak-numeral, speak_numeral, SpeakNumeral, Aural, mSpeakNumeral, eCSSType_Value, PR_FALSE, kSpeakNumeralKTable)
diff --git a/layout/style/nsCSSProperty.h b/layout/style/nsCSSProperty.h
index 2f807a8339c5..128a08258611 100644
--- a/layout/style/nsCSSProperty.h
+++ b/layout/style/nsCSSProperty.h
@@ -67,6 +67,7 @@ enum nsCSSProperty {
 enum nsCSSType {
   eCSSType_Value,
   eCSSType_Rect,
+  eCSSType_ValuePair,
   eCSSType_ValueList,
   eCSSType_CounterData,
   eCSSType_Quotes,
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index bc1449bcb383..18f499fc901b 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -1215,12 +1215,6 @@ static const nsCSSProperty gBorderRightSubpropTable[] = {
   eCSSProperty_UNKNOWN
 };
 
-static const nsCSSProperty gBorderSpacingSubpropTable[] = {
-  eCSSProperty_border_x_spacing,
-  eCSSProperty_border_y_spacing,
-  eCSSProperty_UNKNOWN
-};
-
 static const nsCSSProperty gBorderStyleSubpropTable[] = {
   // Code relies on these being in top-right-bottom-left order.
   eCSSProperty_border_top_style,
@@ -1385,18 +1379,6 @@ static const nsCSSProperty gPauseSubpropTable[] = {
   eCSSProperty_UNKNOWN
 };
 
-static const nsCSSProperty gPlayDuringSubpropTable[] = {
-  eCSSProperty_play_during_uri,
-  eCSSProperty_play_during_flags,
-  eCSSProperty_UNKNOWN
-};
-
-static const nsCSSProperty gSizeSubpropTable[] = {
-  eCSSProperty_size_width,
-  eCSSProperty_size_height,
-  eCSSProperty_UNKNOWN
-};
-
 const nsCSSProperty *const
 nsCSSProps::kSubpropertyTable[eCSSProperty_COUNT - eCSSProperty_COUNT_no_shorthands] = {
     #define CSS_PROP_SHORTHAND(name_, id_, method_) g##method_##SubpropTable,
diff --git a/layout/style/nsCSSStruct.cpp b/layout/style/nsCSSStruct.cpp
index a4cac3eaa957..c6d5b3f6a3b6 100644
--- a/layout/style/nsCSSStruct.cpp
+++ b/layout/style/nsCSSStruct.cpp
@@ -49,6 +49,8 @@
 #include "nsStyleConsts.h"
 
 #include "nsCOMPtr.h"
+#include "nsReadableUtils.h"
+#include "nsPrintfCString.h"
 
 #define CSS_IF_DELETE(ptr)  if (nsnull != ptr)  { delete ptr; ptr = nsnull; }
 
@@ -382,6 +384,25 @@ void nsCSSRect::List(FILE* out, PRInt32 aIndent, const nsCSSProperty aTRBL[]) co
 }
 #endif
 
+// --- nsCSSValuePair -------------------
+#ifdef DEBUG
+void nsCSSValuePair::AppendToString(nsAString& aString,
+                                    nsCSSProperty aPropName) const
+{
+  if (mXValue.GetUnit() != eCSSUnit_Null) {
+    AppendUTF8toUTF16(nsCSSProps::GetStringValue(aPropName), aString);
+    aString.Append(NS_LITERAL_STRING(": "));
+    mXValue.AppendToString(aString);
+    NS_ASSERTION(mYValue.GetUnit() != eCSSUnit_Null,
+                 nsPrintfCString("Parsed half of a %s?",
+                                 nsCSSProps::GetStringValue(aPropName).get()).get());
+    aString.Append(PRUnichar(' '));
+    mYValue.AppendToString(aString);
+  }
+}
+#endif
+
+
 // --- nsCSSValueListRect -----------------
 
 MOZ_DECL_CTOR_COUNTER(nsCSSValueListRect)
@@ -738,8 +759,7 @@ nsCSSTable::nsCSSTable(void)
 
 nsCSSTable::nsCSSTable(const nsCSSTable& aCopy)
   : mBorderCollapse(aCopy.mBorderCollapse),
-    mBorderSpacingX(aCopy.mBorderSpacingX),
-    mBorderSpacingY(aCopy.mBorderSpacingY),
+    mBorderSpacing(aCopy.mBorderSpacing),
     mCaptionSide(aCopy.mCaptionSide),
     mEmptyCells(aCopy.mEmptyCells),
     mLayout(aCopy.mLayout)
@@ -760,8 +780,7 @@ void nsCSSTable::List(FILE* out, PRInt32 aIndent) const
   nsAutoString buffer;
 
   mBorderCollapse.AppendToString(buffer, eCSSProperty_border_collapse);
-  mBorderSpacingX.AppendToString(buffer, eCSSProperty_border_x_spacing);
-  mBorderSpacingY.AppendToString(buffer, eCSSProperty_border_y_spacing);
+  mBorderSpacing.AppendToString(buffer, eCSSProperty_border_spacing);
   mCaptionSide.AppendToString(buffer, eCSSProperty_caption_side);
   mEmptyCells.AppendToString(buffer, eCSSProperty_empty_cells);
   mLayout.AppendToString(buffer, eCSSProperty_table_layout);
@@ -822,8 +841,7 @@ nsCSSPage::nsCSSPage(void)
 
 nsCSSPage::nsCSSPage(const nsCSSPage& aCopy)
   : mMarks(aCopy.mMarks),
-    mSizeWidth(aCopy.mSizeWidth),
-    mSizeHeight(aCopy.mSizeHeight)
+    mSize(aCopy.mSize)
 {
   MOZ_COUNT_CTOR(nsCSSPage);
 }
@@ -841,8 +859,7 @@ void nsCSSPage::List(FILE* out, PRInt32 aIndent) const
   nsAutoString buffer;
 
   mMarks.AppendToString(buffer, eCSSProperty_marks);
-  mSizeWidth.AppendToString(buffer, eCSSProperty_size_width);
-  mSizeHeight.AppendToString(buffer, eCSSProperty_size_height);
+  mSize.AppendToString(buffer, eCSSProperty_size);
 
   fputs(NS_LossyConvertUCS2toASCII(buffer).get(), out);
 }
@@ -1068,7 +1085,6 @@ nsCSSAural::nsCSSAural(const nsCSSAural& aCopy)
     mPitch(aCopy.mPitch),
     mPitchRange(aCopy.mPitchRange),
     mPlayDuring(aCopy.mPlayDuring),
-    mPlayDuringFlags(aCopy.mPlayDuringFlags),
     mRichness(aCopy.mRichness),
     mSpeak(aCopy.mSpeak),
     mSpeakHeader(aCopy.mSpeakHeader),
@@ -1102,8 +1118,7 @@ void nsCSSAural::List(FILE* out, PRInt32 aIndent) const
   mPauseBefore.AppendToString(buffer, eCSSProperty_pause_before);
   mPitch.AppendToString(buffer, eCSSProperty_pitch);
   mPitchRange.AppendToString(buffer, eCSSProperty_pitch_range);
-  mPlayDuring.AppendToString(buffer, eCSSProperty_play_during_uri);
-  mPlayDuringFlags.AppendToString(buffer, eCSSProperty_play_during_flags);
+  mPlayDuring.AppendToString(buffer, eCSSProperty_play_during);
   mRichness.AppendToString(buffer, eCSSProperty_richness);
   mSpeak.AppendToString(buffer, eCSSProperty_speak);
   mSpeakHeader.AppendToString(buffer, eCSSProperty_speak_header);
diff --git a/layout/style/nsCSSStruct.h b/layout/style/nsCSSStruct.h
index ae641fcff599..69c1dee785a4 100644
--- a/layout/style/nsCSSStruct.h
+++ b/layout/style/nsCSSStruct.h
@@ -199,6 +199,47 @@ struct nsCSSRect {
   static const side_type sides[4];
 };
 
+MOZ_DECL_CTOR_COUNTER(nsCSSValuePair)
+
+struct nsCSSValuePair {
+  nsCSSValuePair()
+  {
+    MOZ_COUNT_CTOR(nsCSSValuePair);
+  }
+  nsCSSValuePair(const nsCSSValuePair& aCopy)
+    : mXValue(aCopy.mXValue),
+      mYValue(aCopy.mYValue)
+  { 
+    MOZ_COUNT_CTOR(nsCSSValuePair);
+  }
+  ~nsCSSValuePair()
+  {
+    MOZ_COUNT_DTOR(nsCSSValuePair);
+  }
+
+  PRBool operator==(const nsCSSValuePair& aOther) const {
+    return mXValue == aOther.mXValue &&
+           mYValue == aOther.mYValue;
+  }
+
+  PRBool operator!=(const nsCSSValuePair& aOther) const {
+    return mXValue != aOther.mXValue ||
+           mYValue != aOther.mYValue;
+  }
+
+  void SetBothValuesTo(const nsCSSValue& aValue) {
+    mXValue = aValue;
+    mYValue = aValue;
+  }
+
+#ifdef DEBUG
+  void AppendToString(nsAString& aString, nsCSSProperty aPropName) const;
+#endif
+  
+  nsCSSValue mXValue;
+  nsCSSValue mYValue;
+};
+
 struct nsCSSValueListRect {
   nsCSSValueListRect(void);
   nsCSSValueListRect(const nsCSSValueListRect& aCopy);
@@ -338,8 +379,7 @@ struct nsCSSTable : public nsCSSStruct  { // NEW
 #endif
 
   nsCSSValue mBorderCollapse;
-  nsCSSValue mBorderSpacingX;
-  nsCSSValue mBorderSpacingY;
+  nsCSSValuePair mBorderSpacing;
   nsCSSValue mCaptionSide;
   nsCSSValue mEmptyCells;
   
@@ -384,8 +424,7 @@ struct nsCSSPage : public nsCSSStruct  { // NEW
 #endif
 
   nsCSSValue mMarks;
-  nsCSSValue mSizeWidth;
-  nsCSSValue mSizeHeight;
+  nsCSSValuePair mSize;
 };
 
 struct nsRuleDataPage : public nsCSSPage {
@@ -473,8 +512,7 @@ struct nsCSSAural : public nsCSSStruct  { // NEW
   nsCSSValue mPauseBefore;
   nsCSSValue mPitch;
   nsCSSValue mPitchRange;
-  nsCSSValue mPlayDuring;
-  nsCSSValue mPlayDuringFlags;
+  nsCSSValuePair mPlayDuring; // mXValue is URI, mYValue are flags
   nsCSSValue mRichness;
   nsCSSValue mSpeak;
   nsCSSValue mSpeakHeader;
diff --git a/layout/style/nsComputedDOMStyle.cpp b/layout/style/nsComputedDOMStyle.cpp
index dbdd5b85c352..4be1af210cd0 100644
--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -972,7 +972,41 @@ nsresult
 nsComputedDOMStyle::GetBorderSpacing(nsIFrame *aFrame,
                                      nsIDOMCSSValue** aValue)
 {
-  return NS_ERROR_DOM_NOT_SUPPORTED_ERR;
+  nsDOMCSSValueList *valueList = GetROCSSValueList(PR_FALSE);
+  NS_ENSURE_TRUE(valueList, NS_ERROR_OUT_OF_MEMORY);
+
+  const nsStyleTableBorder *border = nsnull;
+  GetStyleData(eStyleStruct_TableBorder, (const nsStyleStruct*&)border, aFrame);
+  if (border) {
+    nsROCSSPrimitiveValue* xSpacing = GetROCSSPrimitiveValue();
+    if (!xSpacing) {
+      delete valueList;
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    if (!valueList->AppendCSSValue(xSpacing)) {
+      delete valueList;
+      delete xSpacing;
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    
+    nsROCSSPrimitiveValue* ySpacing = GetROCSSPrimitiveValue();
+    if (!ySpacing) {
+      delete valueList;
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+    if (!valueList->AppendCSSValue(ySpacing)) {
+      delete valueList;
+      delete ySpacing;
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    // border-spacing will always be a coord
+    xSpacing->SetTwips(border->mBorderSpacingX.GetCoordValue());
+    ySpacing->SetTwips(border->mBorderSpacingY.GetCoordValue());
+        
+  }
+
+  return CallQueryInterface(valueList, aValue);
 }
 
 nsresult
@@ -3522,7 +3556,7 @@ nsComputedDOMStyle::GetQueryablePropertyMap(PRUint32* aLength)
     COMPUTED_STYLE_MAP_ENTRY(border_right_color,            BorderRightColor),
     COMPUTED_STYLE_MAP_ENTRY(border_right_style,            BorderRightStyle),
     COMPUTED_STYLE_MAP_ENTRY(border_right_width,            BorderRightWidth),
-    //// COMPUTED_STYLE_MAP_ENTRY(border_spacing,           BorderSpacing),
+    COMPUTED_STYLE_MAP_ENTRY(border_spacing,                BorderSpacing),
     //// COMPUTED_STYLE_MAP_ENTRY(border_style,             BorderStyle),
     //// COMPUTED_STYLE_MAP_ENTRY(border_top,               BorderTop),
     COMPUTED_STYLE_MAP_ENTRY(border_top_color,              BorderTopColor),
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index 859041a81fd9..aee9309ad058 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -577,35 +577,43 @@ struct StructCheckData {
   CheckCallbackFn callback;
 };
 
-static void
-ExamineRectProperties(const nsCSSRect* aRect,
-                      PRUint32& aSpecifiedCount, PRUint32& aInheritedCount)
+
+/**
+ * @param aValue the value being examined
+ * @param aSpecifiedCount to be incremented by one if the value is specified
+ * @param aInherited to be incremented by one if the value is set to inherit
+ */
+inline void
+ExamineCSSValue(const nsCSSValue& aValue,
+                PRUint32& aSpecifiedCount, PRUint32& aInheritedCount)
 {
-  if (!aRect)
-    return;
-
-  if (eCSSUnit_Null != aRect->mLeft.GetUnit()) {
-    aSpecifiedCount++;
-    if (eCSSUnit_Inherit == aRect->mLeft.GetUnit())
-      aInheritedCount++;
+  if (aValue.GetUnit() != eCSSUnit_Null) {
+    ++aSpecifiedCount;
+    if (aValue.GetUnit() == eCSSUnit_Inherit) {
+      ++aInheritedCount;
+    }
   }
+}
 
-  if (eCSSUnit_Null != aRect->mTop.GetUnit()) {
-    aSpecifiedCount++;
-    if (eCSSUnit_Inherit == aRect->mTop.GetUnit())
-      aInheritedCount++;
-  }
+static void
+ExamineCSSValuePair(const nsCSSValuePair* aValuePair,
+                    PRUint32& aSpecifiedCount, PRUint32& aInheritedCount)
+{
+  NS_PRECONDITION(aValuePair, "Must have a value pair");
+  
+  ExamineCSSValue(aValuePair->mXValue, aSpecifiedCount, aInheritedCount);
+  ExamineCSSValue(aValuePair->mYValue, aSpecifiedCount, aInheritedCount);
+}
 
-  if (eCSSUnit_Null != aRect->mRight.GetUnit()) {
-    aSpecifiedCount++;
-    if (eCSSUnit_Inherit == aRect->mRight.GetUnit())
-      aInheritedCount++;
-  }
+static void
+ExamineCSSRect(const nsCSSRect* aRect,
+               PRUint32& aSpecifiedCount, PRUint32& aInheritedCount)
+{
+  NS_PRECONDITION(aRect, "Must have a rect");
 
-  if (eCSSUnit_Null != aRect->mBottom.GetUnit()) {
-    aSpecifiedCount++;
-    if (eCSSUnit_Inherit == aRect->mBottom.GetUnit())
-      aInheritedCount++;
+  NS_FOR_CSS_SIDES(side) {
+    ExamineCSSValue(aRect->*(nsCSSRect::sides[side]),
+                    aSpecifiedCount, aInheritedCount);
   }
 }
 
@@ -840,6 +848,13 @@ RectAtOffset(const nsRuleDataStruct& aRuleDataStruct, size_t aOffset)
                      NS_REINTERPRET_CAST(const char*, &aRuleDataStruct) + aOffset);
 }
 
+inline const nsCSSValuePair*
+ValuePairAtOffset(const nsRuleDataStruct& aRuleDataStruct, size_t aOffset)
+{
+  return NS_REINTERPRET_CAST(const nsCSSValuePair*,
+                     NS_REINTERPRET_CAST(const char*, &aRuleDataStruct) + aOffset);
+}
+
 inline const nsCSSValueList*
 ValueListAtOffset(const nsRuleDataStruct& aRuleDataStruct, size_t aOffset)
 {
@@ -893,24 +908,23 @@ nsRuleNode::CheckSpecifiedProperties(const nsStyleStructID aSID,
     switch (prop->type) {
 
       case eCSSType_Value:
-        {
-          ++total;
-          const nsCSSValue& value = ValueAtOffset(aRuleDataStruct, prop->offset);
-          if (eCSSUnit_Null != value.GetUnit()) {
-            ++specified;
-            if (eCSSUnit_Inherit == value.GetUnit()) {
-              ++inherited;
-            }
-          }
-        }
+        ++total;
+        ExamineCSSValue(ValueAtOffset(aRuleDataStruct, prop->offset),
+                        specified, inherited);
         break;
 
       case eCSSType_Rect:
         total += 4;
-        ExamineRectProperties(RectAtOffset(aRuleDataStruct, prop->offset),
-                              specified, inherited);
+        ExamineCSSRect(RectAtOffset(aRuleDataStruct, prop->offset),
+                       specified, inherited);
         break;
 
+      case eCSSType_ValuePair:
+        total += 2;
+        ExamineCSSValuePair(ValuePairAtOffset(aRuleDataStruct, prop->offset),
+                            specified, inherited);
+        break;
+        
       case eCSSType_ValueList:
         {
           ++total;
@@ -3827,18 +3841,18 @@ nsRuleNode::ComputeTableBorderData(nsStyleStruct* aStartStruct,
   nsStyleCoord coord;
 
   // border-spacing-x: length, inherit
-  if (SetCoord(tableData.mBorderSpacingX, coord, coord, SETCOORD_LENGTH, aContext, mPresContext, inherited)) {
+  if (SetCoord(tableData.mBorderSpacing.mXValue, coord, coord, SETCOORD_LENGTH, aContext, mPresContext, inherited)) {
     table->mBorderSpacingX = coord.GetCoordValue();
   }
-  else if (eCSSUnit_Inherit == tableData.mBorderSpacingX.GetUnit()) {
+  else if (eCSSUnit_Inherit == tableData.mBorderSpacing.mXValue.GetUnit()) {
     inherited = PR_TRUE;
     table->mBorderSpacingX = parentTable->mBorderSpacingX;
   }
   // border-spacing-y: length, inherit
-  if (SetCoord(tableData.mBorderSpacingY, coord, coord, SETCOORD_LENGTH, aContext, mPresContext, inherited)) {
+  if (SetCoord(tableData.mBorderSpacing.mYValue, coord, coord, SETCOORD_LENGTH, aContext, mPresContext, inherited)) {
     table->mBorderSpacingY = coord.GetCoordValue();
   }
-  else if (eCSSUnit_Inherit == tableData.mBorderSpacingY.GetUnit()) {
+  else if (eCSSUnit_Inherit == tableData.mBorderSpacing.mYValue.GetUnit()) {
     inherited = PR_TRUE;
     table->mBorderSpacingY = parentTable->mBorderSpacingY;
   }