diff --git a/layout/generic/nsHTMLReflowState.cpp b/layout/generic/nsHTMLReflowState.cpp
index 3e4b0a3f3cf..381212fd26a 100644
--- a/layout/generic/nsHTMLReflowState.cpp
+++ b/layout/generic/nsHTMLReflowState.cpp
@@ -740,7 +740,7 @@ nsHTMLReflowState::InitConstraints(nsIPresContext& aPresContext)
                  (computedMargin.right < 200000), "oy");
 #endif
     ComputeBorderFor(frame, mComputedBorderPadding);
-    ComputePaddingFor(frame, parentReflowState, mComputedPadding);
+    ComputePadding(containingBlockWidth);
     mComputedBorderPadding += mComputedPadding;
 
     nsStyleUnit widthUnit = mStylePosition->mWidth.GetUnit();
@@ -1265,6 +1265,46 @@ nsHTMLReflowState::ComputeMargin(nscoord aContainingBlockWidth)
   }
 }
 
+void
+nsHTMLReflowState::ComputePadding(nscoord aContainingBlockWidth)
+{
+  // If style can provide us the padding directly, then use it.
+#if 0
+  if (!mStyleSpacing->GetPadding(mComputedPadding))
+#else
+  mStyleSpacing->CalcPaddingFor(frame, mComputedPadding);
+  if ((eStyleUnit_Percent == mStyleSpacing->mPadding.GetTopUnit()) ||
+      (eStyleUnit_Percent == mStyleSpacing->mPadding.GetRightUnit()) ||
+      (eStyleUnit_Percent == mStyleSpacing->mPadding.GetBottomUnit()) ||
+      (eStyleUnit_Percent == mStyleSpacing->mPadding.GetLeftUnit()))
+#endif
+  {
+    // We have to compute the value (because it's uncomputable by
+    // the style code).
+    nsStyleCoord left, right, top, bottom;
+    ComputeHorizontalValue(aContainingBlockWidth,
+                           mStyleSpacing->mPadding.GetLeftUnit(),
+                           mStyleSpacing->mPadding.GetLeft(left),
+                           mComputedPadding.left);
+    ComputeHorizontalValue(aContainingBlockWidth,
+                           mStyleSpacing->mPadding.GetRightUnit(),
+                           mStyleSpacing->mPadding.GetRight(right),
+                           mComputedPadding.right);
+
+    // According to the CSS2 spec, padding percentages are
+    // calculated with respect to the *width* of the containing
+    // block, even for padding-top and padding-bottom.
+    ComputeHorizontalValue(aContainingBlockWidth,
+                           mStyleSpacing->mPadding.GetTopUnit(),
+                           mStyleSpacing->mPadding.GetTop(top),
+                           mComputedPadding.top);
+    ComputeHorizontalValue(aContainingBlockWidth,
+                           mStyleSpacing->mPadding.GetBottomUnit(),
+                           mStyleSpacing->mPadding.GetBottom(bottom),
+                           mComputedPadding.bottom);
+  }
+}
+
 void
 nsHTMLReflowState::ComputePaddingFor(nsIFrame* aFrame,
                                      const nsReflowState* aParentRS,
diff --git a/layout/html/base/src/nsHTMLReflowState.cpp b/layout/html/base/src/nsHTMLReflowState.cpp
index 3e4b0a3f3cf..381212fd26a 100644
--- a/layout/html/base/src/nsHTMLReflowState.cpp
+++ b/layout/html/base/src/nsHTMLReflowState.cpp
@@ -740,7 +740,7 @@ nsHTMLReflowState::InitConstraints(nsIPresContext& aPresContext)
                  (computedMargin.right < 200000), "oy");
 #endif
     ComputeBorderFor(frame, mComputedBorderPadding);
-    ComputePaddingFor(frame, parentReflowState, mComputedPadding);
+    ComputePadding(containingBlockWidth);
     mComputedBorderPadding += mComputedPadding;
 
     nsStyleUnit widthUnit = mStylePosition->mWidth.GetUnit();
@@ -1265,6 +1265,46 @@ nsHTMLReflowState::ComputeMargin(nscoord aContainingBlockWidth)
   }
 }
 
+void
+nsHTMLReflowState::ComputePadding(nscoord aContainingBlockWidth)
+{
+  // If style can provide us the padding directly, then use it.
+#if 0
+  if (!mStyleSpacing->GetPadding(mComputedPadding))
+#else
+  mStyleSpacing->CalcPaddingFor(frame, mComputedPadding);
+  if ((eStyleUnit_Percent == mStyleSpacing->mPadding.GetTopUnit()) ||
+      (eStyleUnit_Percent == mStyleSpacing->mPadding.GetRightUnit()) ||
+      (eStyleUnit_Percent == mStyleSpacing->mPadding.GetBottomUnit()) ||
+      (eStyleUnit_Percent == mStyleSpacing->mPadding.GetLeftUnit()))
+#endif
+  {
+    // We have to compute the value (because it's uncomputable by
+    // the style code).
+    nsStyleCoord left, right, top, bottom;
+    ComputeHorizontalValue(aContainingBlockWidth,
+                           mStyleSpacing->mPadding.GetLeftUnit(),
+                           mStyleSpacing->mPadding.GetLeft(left),
+                           mComputedPadding.left);
+    ComputeHorizontalValue(aContainingBlockWidth,
+                           mStyleSpacing->mPadding.GetRightUnit(),
+                           mStyleSpacing->mPadding.GetRight(right),
+                           mComputedPadding.right);
+
+    // According to the CSS2 spec, padding percentages are
+    // calculated with respect to the *width* of the containing
+    // block, even for padding-top and padding-bottom.
+    ComputeHorizontalValue(aContainingBlockWidth,
+                           mStyleSpacing->mPadding.GetTopUnit(),
+                           mStyleSpacing->mPadding.GetTop(top),
+                           mComputedPadding.top);
+    ComputeHorizontalValue(aContainingBlockWidth,
+                           mStyleSpacing->mPadding.GetBottomUnit(),
+                           mStyleSpacing->mPadding.GetBottom(bottom),
+                           mComputedPadding.bottom);
+  }
+}
+
 void
 nsHTMLReflowState::ComputePaddingFor(nsIFrame* aFrame,
                                      const nsReflowState* aParentRS,
diff --git a/layout/html/base/src/nsIHTMLReflow.h b/layout/html/base/src/nsIHTMLReflow.h
index 8e7d84b2287..e1c8d98bf46 100644
--- a/layout/html/base/src/nsIHTMLReflow.h
+++ b/layout/html/base/src/nsIHTMLReflow.h
@@ -345,9 +345,13 @@ protected:
                                            const nsStylePosition* aPosition,
                                            const nsStyleDisplay* aDisplay);
 
-  // Computes margins from the specified margin style information, and
+  // Computes margin values from the specified margin style information, and
   // fills in the mComputedMargin member
   void ComputeMargin(nscoord aContainingBlockWidth);
+  
+  // Computes padding values from the specified padding style information, and
+  // fills in the mComputedPadding member
+  void ComputePadding(nscoord aContainingBlockWidth);
 };
 
 //----------------------------------------------------------------------