diff --git a/layout/html/table/src/BasicTableLayoutStrategy.cpp b/layout/html/table/src/BasicTableLayoutStrategy.cpp
index 7a41775436db..7b53936185e6 100644
--- a/layout/html/table/src/BasicTableLayoutStrategy.cpp
+++ b/layout/html/table/src/BasicTableLayoutStrategy.cpp
@@ -258,6 +258,13 @@ PRBool BasicTableLayoutStrategy::AssignPreliminaryColumnWidths()
     maxColWidthArray = new PRInt32[mNumCols];
   }
 
+  const nsStyleTable* tableStyle;
+  mTableFrame->GetStyleData(eStyleStruct_Table, (const nsStyleStruct*&)tableStyle);
+  nscoord cellPadding=0;
+  if (eStyleUnit_Coord==tableStyle->mCellPadding.GetUnit())
+    cellPadding=tableStyle->mCellPadding.GetCoordValue();
+  if (gsDebug) printf ("table cell padding = %d\n", cellPadding);
+
   PRInt32 numRows = mTableFrame->GetRowCount();
   PRInt32 colIndex, rowIndex;
 
@@ -291,6 +298,7 @@ PRBool BasicTableLayoutStrategy::AssignPreliminaryColumnWidths()
     {
       haveColWidth = PR_TRUE;
       specifiedFixedColWidth = colPosition->mWidth.GetCoordValue();
+      specifiedFixedColWidth += (cellPadding*2);
     }
 
     /* Scan the column, simulatneously assigning column widths
diff --git a/layout/html/table/src/nsTableCellFrame.cpp b/layout/html/table/src/nsTableCellFrame.cpp
index 606e68321779..a0ca2f141ffe 100644
--- a/layout/html/table/src/nsTableCellFrame.cpp
+++ b/layout/html/table/src/nsTableCellFrame.cpp
@@ -345,6 +345,19 @@ NS_METHOD nsTableCellFrame::Reflow(nsIPresContext& aPresContext,
     printf(" content returned desired width %d given avail width %d\n",
             kidSize.width, availSize.width);
   }
+  // Nav4 hack for 0 width cells.  
+  // Empty cells are assigned a width of 3px
+  // see testcase "cellHeights.html"
+  if (0==kidSize.width)
+  {
+    float p2t;
+    aPresContext.GetScaledPixelsToTwips(p2t);
+    kidSize.width=NSIntPixelsToTwips(3, p2t);
+    if (nsnull!=aDesiredSize.maxElementSize && 0==pMaxElementSize->width)
+          pMaxElementSize->width=NSIntPixelsToTwips(3, p2t);
+    if (gsDebug) printf ("setting child width from 0 to %d for nav4 compatibility\n", NSIntPixelsToTwips(1, p2t));
+  }
+  // end Nav4 hack for 0 width cells
 #endif
   if (PR_TRUE==gsDebug || PR_TRUE==gsDebugNT)
   {
@@ -378,34 +391,6 @@ NS_METHOD nsTableCellFrame::Reflow(nsIPresContext& aPresContext,
   // next determine the cell's width
   nscoord cellWidth = kidSize.width;      // at this point, we've factored in the cell's style attributes
 
-  // Nav4 hack for 0 width cells.  If the cell has any content, it must have a desired width of at least 1
-  // see testcase "cellHeights.html"
-  /*
-  if (0==cellWidth)
-  {
-    PRInt32 childCount;
-    mFirstChild->ChildCount(childCount);
-    if (0!=childCount)
-    {
-      nsIFrame *grandChild;
-      mFirstChild->FirstChild(grandChild);
-      grandChild->ChildCount(childCount);
-      if (0!=childCount)
-      {
-        float p2t;
-        aPresContext.GetScaledPixelsToTwips(p2t);
-        nscoord one = ((nscoord)(NSIntPixelsToTwips(1, p2t)));
-        cellWidth = 1;
-        if (gsDebug) 
-          printf ("setting cellWidth=1 because it was 0 but there's some content\n");
-        if (nsnull!=aDesiredSize.maxElementSize && 0==pMaxElementSize->width)
-          pMaxElementSize->width=1; // insets added in below
-      }
-    }
-  }
-  */
-  // end Nav4 hack for 0 width cells
-
   // NAV4 compatibility: only add insets if cell content was not 0 width
   if (0!=cellWidth)
     cellWidth += leftInset + rightInset;    // factor in insets
@@ -459,20 +444,6 @@ NS_METHOD nsTableCellFrame::IR_StyleChanged(nsIPresContext&          aPresContex
     tableFrame->InvalidateFirstPassCache();
   }
 
-  // we are obligated to pass along the reflow command to our children before doing anything else
-  /*
-  nsIFrame *childFrame = mFirstChild;
-  while (nsnull!=childFrame)
-  {
-    nsHTMLReflowState childReflowState(aPresContext, childFrame, aReflowState,
-                                       aReflowState.maxSize, eReflowReason_Incremental);
-    rv = ReflowChild(childFrame, aPresContext, aDesiredSize, childReflowState, aStatus);
-    if (NS_FAILED(rv))
-      break;
-    // the returned desired size is irrelevant, because we'll do a resize reflow in a moment
-    childFrame->GetNextSibling(childFrame);
-  }
-  */
   return rv;
 }
 
diff --git a/layout/html/table/src/nsTableFrame.cpp b/layout/html/table/src/nsTableFrame.cpp
index c1f4b8837967..4d4c3b01dcfc 100644
--- a/layout/html/table/src/nsTableFrame.cpp
+++ b/layout/html/table/src/nsTableFrame.cpp
@@ -2698,7 +2698,13 @@ void nsTableFrame::BalanceColumnWidths(nsIPresContext& aPresContext,
   const nsStylePosition* position =
     (const nsStylePosition*)mStyleContext->GetStyleData(eStyleStruct_Position);
   if (eStyleUnit_Coord==position->mWidth.GetUnit()) 
-    maxWidth = position->mWidth.GetCoordValue();
+  {
+    nscoord coordWidth=0;
+    coordWidth = position->mWidth.GetCoordValue();
+    // NAV4 compatibility:  0-coord-width == auto-width
+    if (0!=coordWidth)
+      maxWidth = coordWidth;
+  }
 
   if (0>maxWidth)  // nonsense style specification
     maxWidth = 0;
@@ -3860,13 +3866,19 @@ PRBool nsTableFrame::TableIsAutoWidth(nsTableFrame *aTableFrame,
       break;
 
     case eStyleUnit_Coord:
-      // XXX: subtract out this table frame's borderpadding?
-      aSpecifiedTableWidth = tablePosition->mWidth.GetCoordValue();
-      aReflowState.frame->GetStyleData(eStyleStruct_Spacing, (const nsStyleStruct *&)spacing);
-      spacing->CalcBorderPaddingFor(aReflowState.frame, borderPadding);
-      aSpecifiedTableWidth -= (borderPadding.right + borderPadding.left);
-      result = PR_FALSE;
-      break;
+    {
+      nscoord coordWidth = tablePosition->mWidth.GetCoordValue();
+      // NAV4 compatibility.  If coord width is 0, do nothing so we get same result as "auto"
+      if (0!=coordWidth)
+      {
+        aSpecifiedTableWidth = coordWidth;
+        aReflowState.frame->GetStyleData(eStyleStruct_Spacing, (const nsStyleStruct *&)spacing);
+        spacing->CalcBorderPaddingFor(aReflowState.frame, borderPadding);
+        aSpecifiedTableWidth -= (borderPadding.right + borderPadding.left);
+        result = PR_FALSE;
+      }
+    }
+    break;
 
     case eStyleUnit_Percent:
       // set aSpecifiedTableWidth to be the given percent of the parent.
diff --git a/layout/html/table/src/nsTableOuterFrame.cpp b/layout/html/table/src/nsTableOuterFrame.cpp
index 964f640baf06..cc2bcd4afc51 100644
--- a/layout/html/table/src/nsTableOuterFrame.cpp
+++ b/layout/html/table/src/nsTableOuterFrame.cpp
@@ -864,6 +864,9 @@ nscoord nsTableOuterFrame::GetTableWidth(const nsHTMLReflowState& aReflowState)
     switch (position->mWidth.GetUnit()) {
     case eStyleUnit_Coord:
       maxWidth = position->mWidth.GetCoordValue();
+      // NAV4 compatibility:  0-coord-width == auto-width
+      if (0==maxWidth)
+        maxWidth = aReflowState.maxSize.width;
       break;
   
     case eStyleUnit_Auto:
@@ -873,6 +876,9 @@ nscoord nsTableOuterFrame::GetTableWidth(const nsHTMLReflowState& aReflowState)
     case eStyleUnit_Percent:
       maxWidth = (nscoord)((float)aReflowState.maxSize.width *
                            position->mWidth.GetPercentValue());
+      // NAV4 compatibility:  0-percent-width == auto-width
+      if (0==maxWidth)
+        maxWidth = aReflowState.maxSize.width;
       break;
 
     case eStyleUnit_Proportional:
diff --git a/layout/tables/BasicTableLayoutStrategy.cpp b/layout/tables/BasicTableLayoutStrategy.cpp
index 7a41775436db..7b53936185e6 100644
--- a/layout/tables/BasicTableLayoutStrategy.cpp
+++ b/layout/tables/BasicTableLayoutStrategy.cpp
@@ -258,6 +258,13 @@ PRBool BasicTableLayoutStrategy::AssignPreliminaryColumnWidths()
     maxColWidthArray = new PRInt32[mNumCols];
   }
 
+  const nsStyleTable* tableStyle;
+  mTableFrame->GetStyleData(eStyleStruct_Table, (const nsStyleStruct*&)tableStyle);
+  nscoord cellPadding=0;
+  if (eStyleUnit_Coord==tableStyle->mCellPadding.GetUnit())
+    cellPadding=tableStyle->mCellPadding.GetCoordValue();
+  if (gsDebug) printf ("table cell padding = %d\n", cellPadding);
+
   PRInt32 numRows = mTableFrame->GetRowCount();
   PRInt32 colIndex, rowIndex;
 
@@ -291,6 +298,7 @@ PRBool BasicTableLayoutStrategy::AssignPreliminaryColumnWidths()
     {
       haveColWidth = PR_TRUE;
       specifiedFixedColWidth = colPosition->mWidth.GetCoordValue();
+      specifiedFixedColWidth += (cellPadding*2);
     }
 
     /* Scan the column, simulatneously assigning column widths
diff --git a/layout/tables/nsTableCellFrame.cpp b/layout/tables/nsTableCellFrame.cpp
index 606e68321779..a0ca2f141ffe 100644
--- a/layout/tables/nsTableCellFrame.cpp
+++ b/layout/tables/nsTableCellFrame.cpp
@@ -345,6 +345,19 @@ NS_METHOD nsTableCellFrame::Reflow(nsIPresContext& aPresContext,
     printf(" content returned desired width %d given avail width %d\n",
             kidSize.width, availSize.width);
   }
+  // Nav4 hack for 0 width cells.  
+  // Empty cells are assigned a width of 3px
+  // see testcase "cellHeights.html"
+  if (0==kidSize.width)
+  {
+    float p2t;
+    aPresContext.GetScaledPixelsToTwips(p2t);
+    kidSize.width=NSIntPixelsToTwips(3, p2t);
+    if (nsnull!=aDesiredSize.maxElementSize && 0==pMaxElementSize->width)
+          pMaxElementSize->width=NSIntPixelsToTwips(3, p2t);
+    if (gsDebug) printf ("setting child width from 0 to %d for nav4 compatibility\n", NSIntPixelsToTwips(1, p2t));
+  }
+  // end Nav4 hack for 0 width cells
 #endif
   if (PR_TRUE==gsDebug || PR_TRUE==gsDebugNT)
   {
@@ -378,34 +391,6 @@ NS_METHOD nsTableCellFrame::Reflow(nsIPresContext& aPresContext,
   // next determine the cell's width
   nscoord cellWidth = kidSize.width;      // at this point, we've factored in the cell's style attributes
 
-  // Nav4 hack for 0 width cells.  If the cell has any content, it must have a desired width of at least 1
-  // see testcase "cellHeights.html"
-  /*
-  if (0==cellWidth)
-  {
-    PRInt32 childCount;
-    mFirstChild->ChildCount(childCount);
-    if (0!=childCount)
-    {
-      nsIFrame *grandChild;
-      mFirstChild->FirstChild(grandChild);
-      grandChild->ChildCount(childCount);
-      if (0!=childCount)
-      {
-        float p2t;
-        aPresContext.GetScaledPixelsToTwips(p2t);
-        nscoord one = ((nscoord)(NSIntPixelsToTwips(1, p2t)));
-        cellWidth = 1;
-        if (gsDebug) 
-          printf ("setting cellWidth=1 because it was 0 but there's some content\n");
-        if (nsnull!=aDesiredSize.maxElementSize && 0==pMaxElementSize->width)
-          pMaxElementSize->width=1; // insets added in below
-      }
-    }
-  }
-  */
-  // end Nav4 hack for 0 width cells
-
   // NAV4 compatibility: only add insets if cell content was not 0 width
   if (0!=cellWidth)
     cellWidth += leftInset + rightInset;    // factor in insets
@@ -459,20 +444,6 @@ NS_METHOD nsTableCellFrame::IR_StyleChanged(nsIPresContext&          aPresContex
     tableFrame->InvalidateFirstPassCache();
   }
 
-  // we are obligated to pass along the reflow command to our children before doing anything else
-  /*
-  nsIFrame *childFrame = mFirstChild;
-  while (nsnull!=childFrame)
-  {
-    nsHTMLReflowState childReflowState(aPresContext, childFrame, aReflowState,
-                                       aReflowState.maxSize, eReflowReason_Incremental);
-    rv = ReflowChild(childFrame, aPresContext, aDesiredSize, childReflowState, aStatus);
-    if (NS_FAILED(rv))
-      break;
-    // the returned desired size is irrelevant, because we'll do a resize reflow in a moment
-    childFrame->GetNextSibling(childFrame);
-  }
-  */
   return rv;
 }
 
diff --git a/layout/tables/nsTableFrame.cpp b/layout/tables/nsTableFrame.cpp
index c1f4b8837967..4d4c3b01dcfc 100644
--- a/layout/tables/nsTableFrame.cpp
+++ b/layout/tables/nsTableFrame.cpp
@@ -2698,7 +2698,13 @@ void nsTableFrame::BalanceColumnWidths(nsIPresContext& aPresContext,
   const nsStylePosition* position =
     (const nsStylePosition*)mStyleContext->GetStyleData(eStyleStruct_Position);
   if (eStyleUnit_Coord==position->mWidth.GetUnit()) 
-    maxWidth = position->mWidth.GetCoordValue();
+  {
+    nscoord coordWidth=0;
+    coordWidth = position->mWidth.GetCoordValue();
+    // NAV4 compatibility:  0-coord-width == auto-width
+    if (0!=coordWidth)
+      maxWidth = coordWidth;
+  }
 
   if (0>maxWidth)  // nonsense style specification
     maxWidth = 0;
@@ -3860,13 +3866,19 @@ PRBool nsTableFrame::TableIsAutoWidth(nsTableFrame *aTableFrame,
       break;
 
     case eStyleUnit_Coord:
-      // XXX: subtract out this table frame's borderpadding?
-      aSpecifiedTableWidth = tablePosition->mWidth.GetCoordValue();
-      aReflowState.frame->GetStyleData(eStyleStruct_Spacing, (const nsStyleStruct *&)spacing);
-      spacing->CalcBorderPaddingFor(aReflowState.frame, borderPadding);
-      aSpecifiedTableWidth -= (borderPadding.right + borderPadding.left);
-      result = PR_FALSE;
-      break;
+    {
+      nscoord coordWidth = tablePosition->mWidth.GetCoordValue();
+      // NAV4 compatibility.  If coord width is 0, do nothing so we get same result as "auto"
+      if (0!=coordWidth)
+      {
+        aSpecifiedTableWidth = coordWidth;
+        aReflowState.frame->GetStyleData(eStyleStruct_Spacing, (const nsStyleStruct *&)spacing);
+        spacing->CalcBorderPaddingFor(aReflowState.frame, borderPadding);
+        aSpecifiedTableWidth -= (borderPadding.right + borderPadding.left);
+        result = PR_FALSE;
+      }
+    }
+    break;
 
     case eStyleUnit_Percent:
       // set aSpecifiedTableWidth to be the given percent of the parent.
diff --git a/layout/tables/nsTableOuterFrame.cpp b/layout/tables/nsTableOuterFrame.cpp
index 964f640baf06..cc2bcd4afc51 100644
--- a/layout/tables/nsTableOuterFrame.cpp
+++ b/layout/tables/nsTableOuterFrame.cpp
@@ -864,6 +864,9 @@ nscoord nsTableOuterFrame::GetTableWidth(const nsHTMLReflowState& aReflowState)
     switch (position->mWidth.GetUnit()) {
     case eStyleUnit_Coord:
       maxWidth = position->mWidth.GetCoordValue();
+      // NAV4 compatibility:  0-coord-width == auto-width
+      if (0==maxWidth)
+        maxWidth = aReflowState.maxSize.width;
       break;
   
     case eStyleUnit_Auto:
@@ -873,6 +876,9 @@ nscoord nsTableOuterFrame::GetTableWidth(const nsHTMLReflowState& aReflowState)
     case eStyleUnit_Percent:
       maxWidth = (nscoord)((float)aReflowState.maxSize.width *
                            position->mWidth.GetPercentValue());
+      // NAV4 compatibility:  0-percent-width == auto-width
+      if (0==maxWidth)
+        maxWidth = aReflowState.maxSize.width;
       break;
 
     case eStyleUnit_Proportional: