diff --git a/mozilla/content/html/style/src/nsCSSLayout.cpp b/mozilla/content/html/style/src/nsCSSLayout.cpp
index d5e6e5bbb40..851cb7aa850 100644
--- a/mozilla/content/html/style/src/nsCSSLayout.cpp
+++ b/mozilla/content/html/style/src/nsCSSLayout.cpp
@@ -26,6 +26,7 @@
 #include "nsIPtr.h"
 
 static NS_DEFINE_IID(kStyleMoleculeSID, NS_STYLEMOLECULE_SID);
+static NS_DEFINE_IID(kStylePositionSID, NS_STYLEPOSITION_SID);
 
 NS_DEF_PTR(nsIStyleContext);
 NS_DEF_PTR(nsIContent);
@@ -224,11 +225,12 @@ void nsCSSLayout::RelativePositionChildren(nsIPresContext* aCX,
 
     kid->GetContent(kidContent.AssignRef());
     kid->GetStyleContext(aCX, kidSC.AssignRef());
-    nsStyleMolecule* kidMol = (nsStyleMolecule*)kidSC->GetData(kStyleMoleculeSID);
-    if (NS_STYLE_POSITION_RELATIVE == kidMol->positionFlags) {
+    nsStylePosition* kidPosition = (nsStylePosition*)kidSC->GetData(kStylePositionSID);
+    if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
       kid->GetOrigin(origin);
-      nscoord dx = kidMol->left;
-      nscoord dy = kidMol->top;
+      // XXX Check the flags: could be auto or percent (not just length)
+      nscoord dx = kidPosition->mLeftOffset;
+      nscoord dy = kidPosition->mTopOffset;
       kid->MoveTo(origin.x + dx, origin.y + dy);
     }
     kid->GetNextSibling(kid);
diff --git a/mozilla/content/html/style/src/nsCSSStyleRule.cpp b/mozilla/content/html/style/src/nsCSSStyleRule.cpp
index fbb30a71c3e..47b43ba421d 100644
--- a/mozilla/content/html/style/src/nsCSSStyleRule.cpp
+++ b/mozilla/content/html/style/src/nsCSSStyleRule.cpp
@@ -668,22 +668,34 @@ void CSSStyleRuleImpl::MapStyleInto(nsIStyleContext* aContext, nsIPresContext* a
           position->mPosition = ourPosition->mPosition.GetIntValue();
         }
 
-        // box offsets
+        // box offsets. note: default value is auto so we don't check for it here
         if (ourPosition->mLeft.IsLengthUnit()) {
           position->mLeftOffset = CalcLength(ourPosition->mLeft, font, aPresContext);
           position->mLeftOffsetFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mHeight.GetUnit() == eCSSUnit_Percent) {
+          position->mLeftOffset = (nscoord)(100 * ourPosition->mLeft.GetFloatValue());
+          position->mLeftOffsetFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
         if (ourPosition->mTop.IsLengthUnit()) {
           position->mTopOffset = CalcLength(ourPosition->mTop, font, aPresContext);
           position->mTopOffsetFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mHeight.GetUnit() == eCSSUnit_Percent) {
+          position->mTopOffset = (nscoord)(100 * ourPosition->mTop.GetFloatValue());
+          position->mTopOffsetFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
         if (ourPosition->mWidth.IsLengthUnit()) {
           position->mWidth = CalcLength(ourPosition->mWidth, font, aPresContext);
           position->mWidthFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mWidth.GetUnit() == eCSSUnit_Percent) {
+          position->mWidth = (nscoord)(100 * ourPosition->mWidth.GetFloatValue());
+          position->mWidthFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
         if (ourPosition->mHeight.IsLengthUnit()) {
           position->mHeight = CalcLength(ourPosition->mHeight, font, aPresContext);
           position->mHeightFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mHeight.GetUnit() == eCSSUnit_Percent) {
+          position->mHeight = (nscoord)(100 * ourPosition->mHeight.GetFloatValue());
+          position->mHeightFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
       }
     }
diff --git a/mozilla/layout/base/public/nsIStyleContext.h b/mozilla/layout/base/public/nsIStyleContext.h
index 2645017fc5d..b934758541b 100644
--- a/mozilla/layout/base/public/nsIStyleContext.h
+++ b/mozilla/layout/base/public/nsIStyleContext.h
@@ -159,8 +159,6 @@ struct nsStyleMolecule : public nsStyleStruct {
   PRInt32 proportionalWidth;
   PRInt32 fixedHeight;
   PRInt32 proportionalHeight;
-  PRUint8 positionFlags;
-  nscoord top, left;
 
 protected:
   // The constructor is protected because you may not make these
diff --git a/mozilla/layout/generic/nsBlockFrame.cpp b/mozilla/layout/generic/nsBlockFrame.cpp
index f8a9f42e1d5..8697f2d49a7 100644
--- a/mozilla/layout/generic/nsBlockFrame.cpp
+++ b/mozilla/layout/generic/nsBlockFrame.cpp
@@ -503,8 +503,13 @@ void nsBlockFrame::AddInlineChildToLine(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+
   PRIntn direction = aState.mol->direction;
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
@@ -592,7 +597,11 @@ void nsBlockFrame::AddBlockChild(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
diff --git a/mozilla/layout/generic/nsBlockReflowState.cpp b/mozilla/layout/generic/nsBlockReflowState.cpp
index f8a9f42e1d5..8697f2d49a7 100644
--- a/mozilla/layout/generic/nsBlockReflowState.cpp
+++ b/mozilla/layout/generic/nsBlockReflowState.cpp
@@ -503,8 +503,13 @@ void nsBlockFrame::AddInlineChildToLine(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+
   PRIntn direction = aState.mol->direction;
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
@@ -592,7 +597,11 @@ void nsBlockFrame::AddBlockChild(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
diff --git a/mozilla/layout/generic/nsBlockReflowState.h b/mozilla/layout/generic/nsBlockReflowState.h
index f8a9f42e1d5..8697f2d49a7 100644
--- a/mozilla/layout/generic/nsBlockReflowState.h
+++ b/mozilla/layout/generic/nsBlockReflowState.h
@@ -503,8 +503,13 @@ void nsBlockFrame::AddInlineChildToLine(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+
   PRIntn direction = aState.mol->direction;
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
@@ -592,7 +597,11 @@ void nsBlockFrame::AddBlockChild(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
diff --git a/mozilla/layout/html/base/src/nsBlockFrame.cpp b/mozilla/layout/html/base/src/nsBlockFrame.cpp
index f8a9f42e1d5..8697f2d49a7 100644
--- a/mozilla/layout/html/base/src/nsBlockFrame.cpp
+++ b/mozilla/layout/html/base/src/nsBlockFrame.cpp
@@ -503,8 +503,13 @@ void nsBlockFrame::AddInlineChildToLine(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+
   PRIntn direction = aState.mol->direction;
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
@@ -592,7 +597,11 @@ void nsBlockFrame::AddBlockChild(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
diff --git a/mozilla/layout/html/base/src/nsBlockReflowState.cpp b/mozilla/layout/html/base/src/nsBlockReflowState.cpp
index f8a9f42e1d5..8697f2d49a7 100644
--- a/mozilla/layout/html/base/src/nsBlockReflowState.cpp
+++ b/mozilla/layout/html/base/src/nsBlockReflowState.cpp
@@ -503,8 +503,13 @@ void nsBlockFrame::AddInlineChildToLine(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+
   PRIntn direction = aState.mol->direction;
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
@@ -592,7 +597,11 @@ void nsBlockFrame::AddBlockChild(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
diff --git a/mozilla/layout/html/base/src/nsBlockReflowState.h b/mozilla/layout/html/base/src/nsBlockReflowState.h
index f8a9f42e1d5..8697f2d49a7 100644
--- a/mozilla/layout/html/base/src/nsBlockReflowState.h
+++ b/mozilla/layout/html/base/src/nsBlockReflowState.h
@@ -503,8 +503,13 @@ void nsBlockFrame::AddInlineChildToLine(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+
   PRIntn direction = aState.mol->direction;
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
@@ -592,7 +597,11 @@ void nsBlockFrame::AddBlockChild(nsIPresContext* aCX,
 {
   NS_PRECONDITION(nsnull != aState.lineStart, "bad line");
 
-  if (NS_STYLE_POSITION_RELATIVE == aKidMol->positionFlags) {
+  nsStylePosition* kidPosition;
+   
+  // Get the position style data
+  aKidFrame->GetStyleData(kStylePositionSID, (nsStyleStruct*&)kidPosition);
+  if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
     aState.needRelativePos = PR_TRUE;
   }
 
diff --git a/mozilla/layout/html/style/src/nsCSSLayout.cpp b/mozilla/layout/html/style/src/nsCSSLayout.cpp
index d5e6e5bbb40..851cb7aa850 100644
--- a/mozilla/layout/html/style/src/nsCSSLayout.cpp
+++ b/mozilla/layout/html/style/src/nsCSSLayout.cpp
@@ -26,6 +26,7 @@
 #include "nsIPtr.h"
 
 static NS_DEFINE_IID(kStyleMoleculeSID, NS_STYLEMOLECULE_SID);
+static NS_DEFINE_IID(kStylePositionSID, NS_STYLEPOSITION_SID);
 
 NS_DEF_PTR(nsIStyleContext);
 NS_DEF_PTR(nsIContent);
@@ -224,11 +225,12 @@ void nsCSSLayout::RelativePositionChildren(nsIPresContext* aCX,
 
     kid->GetContent(kidContent.AssignRef());
     kid->GetStyleContext(aCX, kidSC.AssignRef());
-    nsStyleMolecule* kidMol = (nsStyleMolecule*)kidSC->GetData(kStyleMoleculeSID);
-    if (NS_STYLE_POSITION_RELATIVE == kidMol->positionFlags) {
+    nsStylePosition* kidPosition = (nsStylePosition*)kidSC->GetData(kStylePositionSID);
+    if (NS_STYLE_POSITION_RELATIVE == kidPosition->mPosition) {
       kid->GetOrigin(origin);
-      nscoord dx = kidMol->left;
-      nscoord dy = kidMol->top;
+      // XXX Check the flags: could be auto or percent (not just length)
+      nscoord dx = kidPosition->mLeftOffset;
+      nscoord dy = kidPosition->mTopOffset;
       kid->MoveTo(origin.x + dx, origin.y + dy);
     }
     kid->GetNextSibling(kid);
diff --git a/mozilla/layout/html/style/src/nsCSSStyleRule.cpp b/mozilla/layout/html/style/src/nsCSSStyleRule.cpp
index fbb30a71c3e..47b43ba421d 100644
--- a/mozilla/layout/html/style/src/nsCSSStyleRule.cpp
+++ b/mozilla/layout/html/style/src/nsCSSStyleRule.cpp
@@ -668,22 +668,34 @@ void CSSStyleRuleImpl::MapStyleInto(nsIStyleContext* aContext, nsIPresContext* a
           position->mPosition = ourPosition->mPosition.GetIntValue();
         }
 
-        // box offsets
+        // box offsets. note: default value is auto so we don't check for it here
         if (ourPosition->mLeft.IsLengthUnit()) {
           position->mLeftOffset = CalcLength(ourPosition->mLeft, font, aPresContext);
           position->mLeftOffsetFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mHeight.GetUnit() == eCSSUnit_Percent) {
+          position->mLeftOffset = (nscoord)(100 * ourPosition->mLeft.GetFloatValue());
+          position->mLeftOffsetFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
         if (ourPosition->mTop.IsLengthUnit()) {
           position->mTopOffset = CalcLength(ourPosition->mTop, font, aPresContext);
           position->mTopOffsetFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mHeight.GetUnit() == eCSSUnit_Percent) {
+          position->mTopOffset = (nscoord)(100 * ourPosition->mTop.GetFloatValue());
+          position->mTopOffsetFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
         if (ourPosition->mWidth.IsLengthUnit()) {
           position->mWidth = CalcLength(ourPosition->mWidth, font, aPresContext);
           position->mWidthFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mWidth.GetUnit() == eCSSUnit_Percent) {
+          position->mWidth = (nscoord)(100 * ourPosition->mWidth.GetFloatValue());
+          position->mWidthFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
         if (ourPosition->mHeight.IsLengthUnit()) {
           position->mHeight = CalcLength(ourPosition->mHeight, font, aPresContext);
           position->mHeightFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mHeight.GetUnit() == eCSSUnit_Percent) {
+          position->mHeight = (nscoord)(100 * ourPosition->mHeight.GetFloatValue());
+          position->mHeightFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
       }
     }
diff --git a/mozilla/layout/style/nsCSSStyleRule.cpp b/mozilla/layout/style/nsCSSStyleRule.cpp
index fbb30a71c3e..47b43ba421d 100644
--- a/mozilla/layout/style/nsCSSStyleRule.cpp
+++ b/mozilla/layout/style/nsCSSStyleRule.cpp
@@ -668,22 +668,34 @@ void CSSStyleRuleImpl::MapStyleInto(nsIStyleContext* aContext, nsIPresContext* a
           position->mPosition = ourPosition->mPosition.GetIntValue();
         }
 
-        // box offsets
+        // box offsets. note: default value is auto so we don't check for it here
         if (ourPosition->mLeft.IsLengthUnit()) {
           position->mLeftOffset = CalcLength(ourPosition->mLeft, font, aPresContext);
           position->mLeftOffsetFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mHeight.GetUnit() == eCSSUnit_Percent) {
+          position->mLeftOffset = (nscoord)(100 * ourPosition->mLeft.GetFloatValue());
+          position->mLeftOffsetFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
         if (ourPosition->mTop.IsLengthUnit()) {
           position->mTopOffset = CalcLength(ourPosition->mTop, font, aPresContext);
           position->mTopOffsetFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mHeight.GetUnit() == eCSSUnit_Percent) {
+          position->mTopOffset = (nscoord)(100 * ourPosition->mTop.GetFloatValue());
+          position->mTopOffsetFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
         if (ourPosition->mWidth.IsLengthUnit()) {
           position->mWidth = CalcLength(ourPosition->mWidth, font, aPresContext);
           position->mWidthFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mWidth.GetUnit() == eCSSUnit_Percent) {
+          position->mWidth = (nscoord)(100 * ourPosition->mWidth.GetFloatValue());
+          position->mWidthFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
         if (ourPosition->mHeight.IsLengthUnit()) {
           position->mHeight = CalcLength(ourPosition->mHeight, font, aPresContext);
           position->mHeightFlags = NS_STYLE_POSITION_VALUE_LENGTH;
+        } else if (ourPosition->mHeight.GetUnit() == eCSSUnit_Percent) {
+          position->mHeight = (nscoord)(100 * ourPosition->mHeight.GetFloatValue());
+          position->mHeightFlags = NS_STYLE_POSITION_VALUE_PCT;
         }
       }
     }