diff --git a/content/mathml/content/src/nsMathMLElement.cpp b/content/mathml/content/src/nsMathMLElement.cpp
index 3c80b98e01c4..31055bf5275a 100644
--- a/content/mathml/content/src/nsMathMLElement.cpp
+++ b/content/mathml/content/src/nsMathMLElement.cpp
@@ -402,12 +402,6 @@ nsMathMLElement::MapMathMLAttributesInto(const nsMappedAttributes* aAttributes,
       nscolor color;
       if (value->GetColorValue(color)) {
         aData->mColorData->mBackColor.SetColorValue(color);
-      } else {
-        nsAutoString str(value->GetStringValue());
-        str.CompressWhitespace();
-        if (str.EqualsLiteral("transparent")) {
-          aData->mColorData->mBackColor.SetColorValue(NS_RGBA(0,0,0,0));
-        }
       }
     }
   }
diff --git a/gfx/public/nsColorNameList.h b/gfx/public/nsColorNameList.h
index 0e7b2aaae52f..5ebf548c5a7e 100644
--- a/gfx/public/nsColorNameList.h
+++ b/gfx/public/nsColorNameList.h
@@ -201,6 +201,7 @@ GFX_COLOR(tan, NS_RGB(210, 180, 140))
 GFX_COLOR(teal, NS_RGB(  0, 128, 128))
 GFX_COLOR(thistle, NS_RGB(216, 191, 216))
 GFX_COLOR(tomato, NS_RGB(255,  99,  71))
+GFX_COLOR(transparent, NS_RGBA(0, 0, 0, 0))
 GFX_COLOR(turquoise, NS_RGB( 64, 224, 208))
 GFX_COLOR(violet, NS_RGB(238, 130, 238))
 GFX_COLOR(wheat, NS_RGB(245, 222, 179))
diff --git a/layout/base/nsCSSRendering.cpp b/layout/base/nsCSSRendering.cpp
index 40633626313a..bb70a9845985 100644
--- a/layout/base/nsCSSRendering.cpp
+++ b/layout/base/nsCSSRendering.cpp
@@ -596,14 +596,12 @@ nsCSSRendering::PaintBorder(nsPresContext* aPresContext,
 
   // pull out styles, colors, composite colors
   NS_FOR_CSS_SIDES (i) {
-    PRBool transparent, foreground;
+    PRBool foreground;
     borderStyles[i] = aBorderStyle.GetBorderStyle(i);
-    aBorderStyle.GetBorderColor(i, borderColors[i], transparent, foreground);
+    aBorderStyle.GetBorderColor(i, borderColors[i], foreground);
     aBorderStyle.GetCompositeColors(i, &compositeColors[i]);
 
-    if (transparent)
-      borderColors[i] = 0x0;
-    else if (foreground)
+    if (foreground)
       borderColors[i] = ourColor->mColor;
   }
 
@@ -963,7 +961,7 @@ nsCSSRendering::FindNonTransparentBackground(nsStyleContext* aContext,
   
   while (context) {
     result = context->GetStyleBackground();
-    if (0 == (result->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT))
+    if (NS_GET_A(result->mBackgroundColor) > 0)
       break;
 
     context = context->GetParent();
@@ -1301,7 +1299,7 @@ nsCSSRendering::PaintBackground(nsPresContext* aPresContext,
 
   nsIViewManager* vm = aPresContext->GetViewManager();
 
-  if (canvasColor.mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT) {
+  if (NS_GET_A(canvasColor.mBackgroundColor) == 0) {
     nsIView* rootView;
     vm->GetRootView(rootView);
     if (!rootView->GetParent()) {
@@ -1314,7 +1312,6 @@ nsCSSRendering::PaintBackground(nsPresContext* aPresContext,
       if (!widgetIsTransparent) {
         // Ensure that we always paint a color for the root (in case there's
         // no background at all or a partly transparent image).
-        canvasColor.mBackgroundFlags &= ~NS_STYLE_BG_COLOR_TRANSPARENT;
         canvasColor.mBackgroundColor = aPresContext->DefaultBackgroundColor();
       }
     }
@@ -1414,10 +1411,9 @@ IsSolidBorderEdge(const nsStyleBorder& aBorder, PRUint32 aSide)
     return PR_FALSE;
 
   nscolor color;
-  PRBool isTransparent;
   PRBool isForeground;
-  aBorder.GetBorderColor(aSide, color, isTransparent, isForeground);
-  return !isTransparent && NS_GET_A(color) == 255;
+  aBorder.GetBorderColor(aSide, color, isForeground);
+  return NS_GET_A(color) == 255;
 }
 
 /**
@@ -1590,8 +1586,7 @@ nsCSSRendering::PaintBackgroundWithSC(nsPresContext* aPresContext,
   // on the dirty rect before accounting for the background-position.
   nscoord tileWidth = imageSize.width;
   nscoord tileHeight = imageSize.height;
-  PRBool  needBackgroundColor = !(aColor.mBackgroundFlags &
-                                  NS_STYLE_BG_COLOR_TRANSPARENT);
+  PRBool  needBackgroundColor = NS_GET_A(aColor.mBackgroundColor) > 0;
   PRIntn  repeat = aColor.mBackgroundRepeat;
 
   switch (repeat) {
@@ -2331,7 +2326,7 @@ nsCSSRendering::PaintBackgroundColor(nsPresContext* aPresContext,
   // color if we're not completely transparent.  See the corresponding check
   // for whether we're allowed to paint background images in
   // PaintBackgroundWithSC before the first call to PaintBackgroundColor.
-  if ((aColor.mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT) &&
+  if (NS_GET_A(aColor.mBackgroundColor) == 0 &&
       (aCanPaintNonWhite || aColor.IsTransparent())) {
     // nothing to paint
     return;
diff --git a/layout/base/nsCSSRenderingBorders.cpp b/layout/base/nsCSSRenderingBorders.cpp
index 3692fe81a335..78b41e17be1d 100644
--- a/layout/base/nsCSSRenderingBorders.cpp
+++ b/layout/base/nsCSSRenderingBorders.cpp
@@ -253,31 +253,6 @@ ComputeBorderCornerDimensions(const gfxRect& aOuterRect,
   }
 }
 
-// And this is what we get due to the aRidiculous aPrefix aConvetion
-// aFor aArguments (sic).
-static PRBool
-AreCompositeColorsEqual(nsBorderColors *aA, nsBorderColors *aB)
-{
-  if (aA == aB)
-    return PR_TRUE;
-
-  if (!aA || !aB)
-    return PR_FALSE;
-
-  while (aA && aB) {
-    if (aA->mTransparent != aB->mTransparent)
-      return PR_FALSE;
-    if (!aA->mTransparent && (aA->mColor != aB->mColor))
-      return PR_FALSE;
-    aA = aA->mNext;
-    aB = aB->mNext;
-  }
-
-  // both should be NULL if these are equal, otherwise one
-  // has more colors than another
-  return (aA == aB);
-}
-
 PRBool
 nsCSSBorderRenderer::AreBorderSideFinalStylesSame(PRUint8 aSides)
 {
@@ -295,7 +270,8 @@ nsCSSBorderRenderer::AreBorderSideFinalStylesSame(PRUint8 aSides)
 
     if (mBorderStyles[firstStyle] != mBorderStyles[i] ||
         mBorderColors[firstStyle] != mBorderColors[i] ||
-        !AreCompositeColorsEqual(mCompositeColors[firstStyle], mCompositeColors[i]))
+        !nsBorderColors::Equal(mCompositeColors[firstStyle],
+                               mCompositeColors[i]))
       return PR_FALSE;
   }
 
@@ -692,9 +668,6 @@ ComputeCompositeColorForLine(PRUint32 aLineIndex,
   while (aLineIndex-- && aBorderColors->mNext)
     aBorderColors = aBorderColors->mNext;
 
-  if (aBorderColors->mTransparent)
-    return gfxRGBA(0.0, 0.0, 0.0, 0.0);
-
   return gfxRGBA(aBorderColors->mColor);
 }
 
diff --git a/layout/base/nsDisplayList.cpp b/layout/base/nsDisplayList.cpp
index cea8a32dfd2b..03f18d490405 100644
--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@@ -490,16 +490,16 @@ nsDisplayBackground::IsOpaque(nsDisplayListBuilder* aBuilder) {
   if (mIsThemed)
     return PR_FALSE;
 
-  PRBool isCanvas;
   const nsStyleBackground* bg;
+  PRBool isCanvas; // not used
   PRBool hasBG =
-    nsCSSRendering::FindBackground(mFrame->PresContext(), mFrame, &bg, &isCanvas);
-  if (!hasBG || (bg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT) ||
-      bg->mBackgroundClip != NS_STYLE_BG_CLIP_BORDER ||
-      nsLayoutUtils::HasNonZeroSide(mFrame->GetStyleBorder()->mBorderRadius) ||
-      NS_GET_A(bg->mBackgroundColor) < 255)
-    return PR_FALSE;
-  return PR_TRUE;
+    nsCSSRendering::FindBackground(mFrame->PresContext(), mFrame,
+                                   &bg, &isCanvas);
+
+  return (hasBG && NS_GET_A(bg->mBackgroundColor) == 255 &&
+          bg->mBackgroundClip == NS_STYLE_BG_CLIP_BORDER &&
+          !nsLayoutUtils::HasNonZeroSide(mFrame->GetStyleBorder()->
+                                         mBorderRadius));
 }
 
 PRBool
diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index b69473471ba6..e58826ddfcfb 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -2725,8 +2725,6 @@ nsLayoutUtils::GetFrameTransparency(nsIFrame* aFrame) {
   const nsStyleBackground* bg;
   if (!nsCSSRendering::FindBackground(aFrame->PresContext(), aFrame, &bg, &isCanvas))
     return eTransparencyTransparent;
-  if (bg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT)
-    return eTransparencyTransparent;
   if (NS_GET_A(bg->mBackgroundColor) < 255)
     return eTransparencyTransparent;
   if (bg->mBackgroundClip != NS_STYLE_BG_CLIP_BORDER)
diff --git a/layout/base/nsStyleConsts.h b/layout/base/nsStyleConsts.h
index 84de9c5b3007..30dc0000c1c5 100644
--- a/layout/base/nsStyleConsts.h
+++ b/layout/base/nsStyleConsts.h
@@ -193,11 +193,10 @@
 #define NS_STYLE_VOLUME_X_LOUD            5
 
 // See nsStyleColor
-#define NS_STYLE_COLOR_TRANSPARENT        0
+#define NS_STYLE_COLOR_MOZ_USE_TEXT_COLOR      1
 #ifdef GFX_HAS_INVERT
-#define NS_STYLE_COLOR_INVERT             1
+#define NS_STYLE_COLOR_INVERT             2
 #endif
-#define NS_STYLE_COLOR_MOZ_USE_TEXT_COLOR      2
 
 // See nsStyleColor
 #define NS_COLOR_MOZ_HYPERLINKTEXT              -1
@@ -206,7 +205,7 @@
 #define NS_COLOR_CURRENTCOLOR                   -4
 
 // See nsStyleBackground
-#define NS_STYLE_BG_COLOR_TRANSPARENT           0x01
+// 0x01 was background-color:transparent
 #define NS_STYLE_BG_IMAGE_NONE                  0x02
 #define NS_STYLE_BG_X_POSITION_PERCENT          0x04
 #define NS_STYLE_BG_X_POSITION_LENGTH           0x08
diff --git a/layout/generic/nsTextFrameThebes.cpp b/layout/generic/nsTextFrameThebes.cpp
index 6b701ad979e2..6f17c918f079 100644
--- a/layout/generic/nsTextFrameThebes.cpp
+++ b/layout/generic/nsTextFrameThebes.cpp
@@ -3036,9 +3036,6 @@ nsTextPaintStyle::InitSelectionColors()
     if (sc) {
       const nsStyleBackground* bg = sc->GetStyleBackground();
       mSelectionBGColor = bg->mBackgroundColor;
-      if (bg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT) {
-        mSelectionBGColor = NS_RGBA(0,0,0,0);
-      }
       mSelectionTextColor = sc->GetStyleColor()->mColor;
       return PR_TRUE;
     }
diff --git a/layout/mathml/base/src/nsMathMLChar.cpp b/layout/mathml/base/src/nsMathMLChar.cpp
index ef3324c05347..0219db0d281c 100644
--- a/layout/mathml/base/src/nsMathMLChar.cpp
+++ b/layout/mathml/base/src/nsMathMLChar.cpp
@@ -2047,7 +2047,7 @@ nsMathMLChar::Display(nsDisplayListBuilder*   aBuilder,
   else if (mRect.width && mRect.height) {
     const nsStyleBackground* backg = styleContext->GetStyleBackground();
     if (styleContext != parentContext &&
-        0 == (backg->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT)) {
+        NS_GET_A(backg->mBackgroundColor) > 0) {
       rv = aLists.BorderBackground()->AppendNewToTop(new (aBuilder)
           nsDisplayMathMLCharBackground(aForFrame, mRect, styleContext));
       NS_ENSURE_SUCCESS(rv, rv);
diff --git a/layout/style/nsCSSDataBlock.cpp b/layout/style/nsCSSDataBlock.cpp
index 14e8b8993879..9eab88c2a7ac 100644
--- a/layout/style/nsCSSDataBlock.cpp
+++ b/layout/style/nsCSSDataBlock.cpp
@@ -233,10 +233,20 @@ nsCSSCompressedDataBlock::MapRuleInfoInto(nsRuleData *aRuleData) const
                                 if (iProp == eCSSProperty_background_color) {
                                     // Force non-'transparent' background
                                     // colors to the user's default.
+                                    // We have the value in the form it was
+                                    // specified at this point, so we have to
+                                    // look for both the keyword 'transparent'
+                                    // and its equivalent in rgba notation.
                                     nsCSSUnit u = target->GetUnit();
-                                    if (u != eCSSUnit_Enumerated &&
-                                        u != eCSSUnit_Inherit &&
-                                        u != eCSSUnit_Initial) {
+                                    nsDependentString buf;
+                                    
+                                    if ((u == eCSSUnit_Color &&
+                                         NS_GET_A(target->GetColorValue())
+                                         > 0) ||
+                                        (u == eCSSUnit_String &&
+                                         !nsGkAtoms::transparent->
+                                         Equals(target->GetStringValue(buf))) ||
+                                        (u == eCSSUnit_EnumColor)) {
                                         target->SetColorValue(aRuleData->
                                             mPresContext->
                                             DefaultBackgroundColor());
diff --git a/layout/style/nsCSSKeywordList.h b/layout/style/nsCSSKeywordList.h
index 502f6e679eb1..b0eb9c00ba82 100644
--- a/layout/style/nsCSSKeywordList.h
+++ b/layout/style/nsCSSKeywordList.h
@@ -450,7 +450,6 @@ CSS_KEY(threedshadow, threedshadow)
 CSS_KEY(toggle, toggle)
 CSS_KEY(top, top)
 CSS_KEY(top-outside, top_outside)
-CSS_KEY(transparent, transparent)
 CSS_KEY(tri-state, tri_state)
 CSS_KEY(ultra-condensed, ultra_condensed)
 CSS_KEY(ultra-expanded, ultra_expanded)
diff --git a/layout/style/nsCSSParser.cpp b/layout/style/nsCSSParser.cpp
index 115096d81e61..55f5d956f732 100644
--- a/layout/style/nsCSSParser.cpp
+++ b/layout/style/nsCSSParser.cpp
@@ -3423,14 +3423,6 @@ CSSParserImpl::ParseColor(nsCSSValue& aValue)
         nsCSSKeyword keyword = nsCSSKeywords::LookupKeyword(tk->mIdent);
         if (eCSSKeyword_UNKNOWN < keyword) { // known keyword
           PRInt32 value;
-          // XXX Now that non-cairo is no longer supported, we should remove
-          // the special parsing of transparent for background-color and
-          // border-color.  (It currently overrides this, since keywords
-          // are checked earlier in ParseVariant.)
-          if (keyword == eCSSKeyword_transparent) {
-            aValue.SetColorValue(NS_RGBA(0, 0, 0, 0));
-            return PR_TRUE;
-          }
           if (nsCSSProps::FindKeyword(keyword, nsCSSProps::kColorKTable, value)) {
             aValue.SetIntValue(value, eCSSUnit_EnumColor);
             return PR_TRUE;
@@ -5061,8 +5053,7 @@ CSSParserImpl::ParseSingleValueProperty(nsCSSValue& aValue,
     return ParseVariant(aValue, VARIANT_HK,
                         nsCSSProps::kBackgroundClipKTable);
   case eCSSProperty_background_color:
-    return ParseVariant(aValue, VARIANT_HCK,
-                        nsCSSProps::kBackgroundColorKTable);
+    return ParseVariant(aValue, VARIANT_HC, nsnull);
   case eCSSProperty_background_image:
     return ParseVariant(aValue, VARIANT_HUO, nsnull);
   case eCSSProperty__moz_background_inline_policy:
@@ -5608,8 +5599,7 @@ CSSParserImpl::ParseBackground()
 
   // Fill in the values that the shorthand will set if we don't find
   // other values.
-  mTempData.mColor.mBackColor.SetIntValue(NS_STYLE_BG_COLOR_TRANSPARENT,
-                                          eCSSUnit_Enumerated);
+  mTempData.mColor.mBackColor.SetColorValue(NS_RGBA(0, 0, 0, 0));
   mTempData.SetPropertyBit(eCSSProperty_background_color);
   mTempData.mColor.mBackImage.SetNoneValue();
   mTempData.SetPropertyBit(eCSSProperty_background_image);
diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 339686b39907..c204004cde8d 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -276,7 +276,7 @@ CSS_PROP_BACKENDONLY(azimuth, azimuth, Azimuth, Aural, mAzimuth, eCSSType_Value,
 CSS_PROP_SHORTHAND(background, background, Background)
 CSS_PROP_BACKGROUND(background-attachment, background_attachment, BackgroundAttachment, Color, mBackAttachment, eCSSType_Value, kBackgroundAttachmentKTable)
 CSS_PROP_BACKGROUND(-moz-background-clip, _moz_background_clip, MozBackgroundClip, Color, mBackClip, eCSSType_Value, kBackgroundClipKTable)
-CSS_PROP_BACKGROUND(background-color, background_color, BackgroundColor, Color, mBackColor, eCSSType_Value, kBackgroundColorKTable)
+CSS_PROP_BACKGROUND(background-color, background_color, BackgroundColor, Color, mBackColor, eCSSType_Value, nsnull)
 CSS_PROP_BACKGROUND(background-image, background_image, BackgroundImage, Color, mBackImage, eCSSType_Value, nsnull)
 CSS_PROP_BACKGROUND(-moz-background-inline-policy, _moz_background_inline_policy, MozBackgroundInlinePolicy, Color, mBackInlinePolicy, eCSSType_Value, kBackgroundInlinePolicyKTable)
 CSS_PROP_BACKGROUND(-moz-background-origin, _moz_background_origin, MozBackgroundOrigin, Color, mBackOrigin, eCSSType_Value, kBackgroundOriginKTable)
diff --git a/layout/style/nsCSSProps.cpp b/layout/style/nsCSSProps.cpp
index 10d22f094e32..ec9a49cb7e95 100644
--- a/layout/style/nsCSSProps.cpp
+++ b/layout/style/nsCSSProps.cpp
@@ -354,11 +354,6 @@ const PRInt32 nsCSSProps::kBackgroundAttachmentKTable[] = {
   eCSSKeyword_UNKNOWN,-1
 };
 
-const PRInt32 nsCSSProps::kBackgroundColorKTable[] = {
-  eCSSKeyword_transparent, NS_STYLE_BG_COLOR_TRANSPARENT,
-  eCSSKeyword_UNKNOWN,-1
-};
-
 const PRInt32 nsCSSProps::kBackgroundClipKTable[] = {
   eCSSKeyword_border,     NS_STYLE_BG_CLIP_BORDER,
   eCSSKeyword_padding,    NS_STYLE_BG_CLIP_PADDING,
@@ -406,7 +401,6 @@ const PRInt32 nsCSSProps::kBorderCollapseKTable[] = {
 };
 
 const PRInt32 nsCSSProps::kBorderColorKTable[] = {
-  eCSSKeyword_transparent, NS_STYLE_COLOR_TRANSPARENT,
   eCSSKeyword__moz_use_text_color, NS_STYLE_COLOR_MOZ_USE_TEXT_COLOR,
   eCSSKeyword_UNKNOWN,-1
 };
diff --git a/layout/style/nsCSSProps.h b/layout/style/nsCSSProps.h
index 26b7793f8f44..4d36dd24ae06 100644
--- a/layout/style/nsCSSProps.h
+++ b/layout/style/nsCSSProps.h
@@ -120,7 +120,6 @@ public:
   static const PRInt32 kAzimuthKTable[];
   static const PRInt32 kBackgroundAttachmentKTable[];
   static const PRInt32 kBackgroundClipKTable[];
-  static const PRInt32 kBackgroundColorKTable[];
   static const PRInt32 kBackgroundInlinePolicyKTable[];
   static const PRInt32 kBackgroundOriginKTable[];
   static const PRInt32 kBackgroundPositionKTable[];
diff --git a/layout/style/nsComputedDOMStyle.cpp b/layout/style/nsComputedDOMStyle.cpp
index 22e88d92ad79..502de3a821ae 100644
--- a/layout/style/nsComputedDOMStyle.cpp
+++ b/layout/style/nsComputedDOMStyle.cpp
@@ -1056,18 +1056,10 @@ nsComputedDOMStyle::GetBackgroundColor(nsIDOMCSSValue** aValue)
   NS_ENSURE_TRUE(val, NS_ERROR_OUT_OF_MEMORY);
 
   const nsStyleBackground* color = GetStyleBackground();
-
-  if (color->mBackgroundFlags & NS_STYLE_BG_COLOR_TRANSPARENT) {
-    const nsAFlatCString& backgroundColor =
-      nsCSSProps::ValueToKeyword(NS_STYLE_BG_COLOR_TRANSPARENT,
-                                 nsCSSProps::kBackgroundColorKTable);
-    val->SetIdent(backgroundColor);
-  } else {
-    nsresult rv = SetToRGBAColor(val, color->mBackgroundColor);
-    if (NS_FAILED(rv)) {
-      delete val;
-      return rv;
-    }
+  nsresult rv = SetToRGBAColor(val, color->mBackgroundColor);
+  if (NS_FAILED(rv)) {
+    delete val;
+    return rv;
   }
 
   return CallQueryInterface(val, aValue);
@@ -3055,15 +3047,11 @@ nsComputedDOMStyle::GetBorderColorsFor(PRUint8 aSide, nsIDOMCSSValue** aValue)
 
           return NS_ERROR_OUT_OF_MEMORY;
         }
-        if (borderColors->mTransparent) {
-          primitive->SetIdent(nsGkAtoms::transparent);
-        } else {
-          nsresult rv = SetToRGBAColor(primitive, borderColors->mColor);
-          if (NS_FAILED(rv)) {
-            delete valueList;
-            delete primitive;
-            return rv;
-          }
+        nsresult rv = SetToRGBAColor(primitive, borderColors->mColor);
+        if (NS_FAILED(rv)) {
+          delete valueList;
+          delete primitive;
+          return rv;
         }
 
         PRBool success = valueList->AppendCSSValue(primitive);
@@ -3125,23 +3113,16 @@ nsComputedDOMStyle::GetBorderColorFor(PRUint8 aSide, nsIDOMCSSValue** aValue)
   NS_ENSURE_TRUE(val, NS_ERROR_OUT_OF_MEMORY);
 
   nscolor color; 
-  PRBool transparent;
   PRBool foreground;
-  GetStyleBorder()->GetBorderColor(aSide, color, transparent, foreground);
-  if (transparent) {
-    val->SetIdent(nsGkAtoms::transparent);
-  } else {
-    if (foreground) {
-      const nsStyleColor* colorStruct = GetStyleColor();
-      color = colorStruct->mColor;
-    }
-    // XXX else?
+  GetStyleBorder()->GetBorderColor(aSide, color, foreground);
+  if (foreground) {
+    color = GetStyleColor()->mColor;
+  }
 
-    nsresult rv = SetToRGBAColor(val, color);
-    if (NS_FAILED(rv)) {
-      delete val;
-      return rv;
-    }
+  nsresult rv = SetToRGBAColor(val, color);
+  if (NS_FAILED(rv)) {
+    delete val;
+    return rv;
   }
 
   return CallQueryInterface(val, aValue);
diff --git a/layout/style/nsHTMLStyleSheet.cpp b/layout/style/nsHTMLStyleSheet.cpp
index 06d3174e2dc9..5fc5c07450e9 100644
--- a/layout/style/nsHTMLStyleSheet.cpp
+++ b/layout/style/nsHTMLStyleSheet.cpp
@@ -187,13 +187,13 @@ ProcessTableRulesAttribute(void*       aStyleStruct,
       borderData->SetBorderStyle(aSide, bStyle);
 
       nscolor borderColor;
-      PRBool transparent, foreground;
-      borderData->GetBorderColor(aSide, borderColor, transparent, foreground);
-      if (transparent || foreground) {
+      PRBool foreground;
+      borderData->GetBorderColor(aSide, borderColor, foreground);
+      if (NS_GET_A(borderColor) == 0 || foreground) {
         // use the table's border color if it is set, otherwise use black
         nscolor tableBorderColor;
-        tableBorderData->GetBorderColor(aSide, tableBorderColor, transparent, foreground);
-        borderColor = (transparent || foreground) ? NS_RGB(0,0,0) : tableBorderColor;
+        tableBorderData->GetBorderColor(aSide, tableBorderColor, foreground);
+        borderColor = (NS_GET_A(borderColor) == 0 || foreground) ? NS_RGB(0,0,0) : tableBorderColor;
         borderData->SetBorderColor(aSide, borderColor);
       }
       // set the border width to be 1 pixel
diff --git a/layout/style/nsRuleNode.cpp b/layout/style/nsRuleNode.cpp
index 007dc1d5d81c..2f3353f69f4b 100644
--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -1719,7 +1719,7 @@ nsRuleNode::SetDefaultOnRoot(const nsStyleStructID aSID, nsStyleContext* aContex
     }
     case eStyleStruct_Background:
     {
-      nsStyleBackground* bg = new (mPresContext) nsStyleBackground(mPresContext);
+      nsStyleBackground* bg = new (mPresContext) nsStyleBackground();
       if (NS_LIKELY(bg != nsnull)) {
         aContext->SetStyle(eStyleStruct_Background, bg);
       }
@@ -3397,28 +3397,22 @@ nsRuleNode::ComputeBackgroundData(void* aStartStruct,
                                   const nsRuleDataStruct& aData, 
                                   nsStyleContext* aContext, 
                                   nsRuleNode* aHighestNode,
-                                  const RuleDetail aRuleDetail, PRBool aInherited)
+                                  const RuleDetail aRuleDetail,
+                                  PRBool aInherited)
 {
-  COMPUTE_START_RESET(Background, (mPresContext), bg, parentBG,
-                      Color, colorData)
+  COMPUTE_START_RESET(Background, (), bg, parentBG, Color, colorData)
 
   // save parentFlags in case bg == parentBG and we clobber them later
   PRUint8 parentFlags = parentBG->mBackgroundFlags;
 
-  // background-color: color, string, enum (flags), inherit
-  if (eCSSUnit_Inherit == colorData.mBackColor.GetUnit()) { // do inherit first, so SetColor doesn't do it
-    bg->mBackgroundColor = parentBG->mBackgroundColor;
-    bg->mBackgroundFlags &= ~NS_STYLE_BG_COLOR_TRANSPARENT;
-    bg->mBackgroundFlags |= (parentFlags & NS_STYLE_BG_COLOR_TRANSPARENT);
-    inherited = PR_TRUE;
-  }
-  else if (SetColor(colorData.mBackColor, parentBG->mBackgroundColor, 
-                    mPresContext, aContext, bg->mBackgroundColor, inherited)) {
-    bg->mBackgroundFlags &= ~NS_STYLE_BG_COLOR_TRANSPARENT;
-  }
-  else if (eCSSUnit_Enumerated == colorData.mBackColor.GetUnit() ||
-           eCSSUnit_Initial == colorData.mBackColor.GetUnit()) {
-    bg->mBackgroundFlags |= NS_STYLE_BG_COLOR_TRANSPARENT;
+  // background-color: color, string, inherit
+  if (eCSSUnit_Initial == colorData.mBackColor.GetUnit()) {
+    bg->mBackgroundColor = NS_RGBA(0, 0, 0, 0);
+  } else if (!SetColor(colorData.mBackColor, parentBG->mBackgroundColor,
+                       mPresContext, aContext, bg->mBackgroundColor,
+                       inherited)) {
+    NS_ASSERTION(eCSSUnit_Null == colorData.mBackColor.GetUnit(),
+                 "unexpected color unit");
   }
 
   // background-image: url (stored as image), none, inherit
@@ -3708,11 +3702,9 @@ nsRuleNode::ComputeBorderData(void* aStartStruct,
         border->EnsureBorderColors();
         border->ClearBorderColors(side);
         while (list) {
-          if (SetColor(list->mValue, unused, mPresContext, aContext, borderColor, inherited))
-            border->AppendBorderColor(side, borderColor, PR_FALSE);
-          else if (eCSSUnit_Enumerated == list->mValue.GetUnit() &&
-                   NS_STYLE_COLOR_TRANSPARENT == list->mValue.GetIntValue())
-            border->AppendBorderColor(side, nsnull, PR_TRUE);
+          if (SetColor(list->mValue, unused, mPresContext,
+                       aContext, borderColor, inherited))
+            border->AppendBorderColor(side, borderColor);
           list = list->mNext;
         }
       }
@@ -3721,7 +3713,6 @@ nsRuleNode::ComputeBorderData(void* aStartStruct,
 
   // border-color, border-*-color: color, string, enum, inherit
   nsCSSRect ourBorderColor(marginData.mBorderColor);
-  PRBool transparent;
   PRBool foreground;
   AdjustLogicalBoxProp(aContext,
                        marginData.mBorderLeftColorLTRSource,
@@ -3739,11 +3730,8 @@ nsRuleNode::ComputeBorderData(void* aStartStruct,
       if (eCSSUnit_Inherit == value.GetUnit()) {
         if (parentContext) {
           inherited = PR_TRUE;
-          parentBorder->GetBorderColor(side, borderColor,
-                                       transparent, foreground);
-          if (transparent)
-            border->SetBorderTransparent(side);
-          else if (foreground) {
+          parentBorder->GetBorderColor(side, borderColor, foreground);
+          if (foreground) {
             // We want to inherit the color from the parent, not use the
             // color on the element where this chunk of style data will be
             // used.  We can ensure that the data for the parent are fully
@@ -3762,9 +3750,6 @@ nsRuleNode::ComputeBorderData(void* aStartStruct,
       }
       else if (eCSSUnit_Enumerated == value.GetUnit()) {
         switch (value.GetIntValue()) {
-          case NS_STYLE_COLOR_TRANSPARENT:
-            border->SetBorderTransparent(side);
-            break;
           case NS_STYLE_COLOR_MOZ_USE_TEXT_COLOR:
             border->SetBorderToForeground(side);
             break;
diff --git a/layout/style/nsStyleStruct.cpp b/layout/style/nsStyleStruct.cpp
index 8a788bf1c5a0..1657b201d004 100644
--- a/layout/style/nsStyleStruct.cpp
+++ b/layout/style/nsStyleStruct.cpp
@@ -468,11 +468,9 @@ nsChangeHint nsStyleBorder::CalcDifference(const nsStyleBorder& aOther) const
     // aOther.mBorderColors
     if (mBorderColors) {
       NS_FOR_CSS_SIDES(ix) {
-        if (!mBorderColors[ix] != !aOther.mBorderColors[ix]) {
+        if (!nsBorderColors::Equal(mBorderColors[ix],
+                                   aOther.mBorderColors[ix])) {
           return NS_STYLE_HINT_VISUAL;
-        } else if (mBorderColors[ix] && aOther.mBorderColors[ix]) {
-          if (!mBorderColors[ix]->Equals(aOther.mBorderColors[ix]))
-            return NS_STYLE_HINT_VISUAL;
         }
       }
     }
@@ -1154,15 +1152,15 @@ nsChangeHint nsStyleColor::MaxDifference()
 // nsStyleBackground
 //
 
-nsStyleBackground::nsStyleBackground(nsPresContext* aPresContext)
-  : mBackgroundFlags(NS_STYLE_BG_COLOR_TRANSPARENT | NS_STYLE_BG_IMAGE_NONE),
+nsStyleBackground::nsStyleBackground()
+  : mBackgroundFlags(NS_STYLE_BG_IMAGE_NONE),
     mBackgroundAttachment(NS_STYLE_BG_ATTACHMENT_SCROLL),
     mBackgroundClip(NS_STYLE_BG_CLIP_BORDER),
     mBackgroundInlinePolicy(NS_STYLE_BG_INLINE_POLICY_CONTINUOUS),
     mBackgroundOrigin(NS_STYLE_BG_ORIGIN_PADDING),
-    mBackgroundRepeat(NS_STYLE_BG_REPEAT_XY)
+    mBackgroundRepeat(NS_STYLE_BG_REPEAT_XY),
+    mBackgroundColor(NS_RGBA(0, 0, 0, 0))
 {
-  mBackgroundColor = aPresContext->DefaultBackgroundColor();
 }
 
 nsStyleBackground::nsStyleBackground(const nsStyleBackground& aSource)
diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index ca56907bc53b..12f631bd4d9f 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -144,7 +144,7 @@ struct nsStyleColor {
 };
 
 struct nsStyleBackground {
-  nsStyleBackground(nsPresContext* aPresContext);
+  nsStyleBackground();
   nsStyleBackground(const nsStyleBackground& aOther);
   ~nsStyleBackground();
 
@@ -179,11 +179,11 @@ struct nsStyleBackground {
   nscolor mBackgroundColor;       // [reset]
   nsCOMPtr<imgIRequest> mBackgroundImage; // [reset]
 
+  // True if this background is completely transparent.
   PRBool IsTransparent() const
   {
-    return (mBackgroundFlags &
-            (NS_STYLE_BG_COLOR_TRANSPARENT | NS_STYLE_BG_IMAGE_NONE)) ==
-            (NS_STYLE_BG_COLOR_TRANSPARENT | NS_STYLE_BG_IMAGE_NONE);
+    return (NS_GET_A(mBackgroundColor) == 0 &&
+            (mBackgroundFlags & NS_STYLE_BG_IMAGE_NONE));
   }
 
   // We have to take slower codepaths for fixed background attachment,
@@ -193,11 +193,10 @@ struct nsStyleBackground {
   PRBool HasFixedBackground() const;
 };
 
-#define BORDER_COLOR_TRANSPARENT  0x40
 #define BORDER_COLOR_FOREGROUND   0x20
 #define OUTLINE_COLOR_INITIAL     0x80
-// TRANSPARENT | FOREGROUND | INITIAL(OUTLINE)
-#define BORDER_COLOR_SPECIAL      0xE0
+// FOREGROUND | INITIAL(OUTLINE)
+#define BORDER_COLOR_SPECIAL      0xA0
 #define BORDER_STYLE_MASK         0x1F
 
 #define NS_SPACING_MARGIN   0
@@ -269,20 +268,18 @@ protected:
 struct nsBorderColors {
   nsBorderColors* mNext;
   nscolor mColor;
-  PRBool mTransparent;
 
   nsBorderColors* CopyColors() {
     nsBorderColors* next = nsnull;
     if (mNext)
       next = mNext->CopyColors();
-    return new nsBorderColors(mColor, mTransparent, next);
+    return new nsBorderColors(mColor, next);
   }
 
   nsBorderColors() :mNext(nsnull) { mColor = NS_RGB(0,0,0); }
 
-  nsBorderColors(const nscolor& aColor, PRBool aTransparent, nsBorderColors* aNext=nsnull) {
+  nsBorderColors(const nscolor& aColor, nsBorderColors* aNext=nsnull) {
     mColor = aColor;
-    mTransparent = aTransparent;
     mNext = aNext;
   }
 
@@ -290,16 +287,18 @@ struct nsBorderColors {
     delete mNext;
   }
 
-  PRBool Equals(nsBorderColors* aOther) {
-    nsBorderColors* c1 = this;
-    nsBorderColors* c2 = aOther;
+  static PRBool Equal(const nsBorderColors* c1,
+                      const nsBorderColors* c2) {
+    if (c1 == c2)
+      return PR_TRUE;
     while (c1 && c2) {
-      if (c1->mColor != c2->mColor ||
-          c1->mTransparent != c2->mTransparent)
+      if (c1->mColor != c2->mColor)
         return PR_FALSE;
       c1 = c1->mNext;
       c2 = c2->mNext;
     }
+    // both should be NULL if these are equal, otherwise one
+    // has more colors than another
     return !c1 && !c2;
   }
 };
@@ -510,16 +509,16 @@ struct nsStyleBorder {
   inline PRBool IsBorderImageLoaded() const;
 
   void GetBorderColor(PRUint8 aSide, nscolor& aColor,
-                      PRBool& aTransparent, PRBool& aForeground) const
+                      PRBool& aForeground) const
   {
-    aTransparent = aForeground = PR_FALSE;
+    aForeground = PR_FALSE;
     NS_ASSERTION(aSide <= NS_SIDE_LEFT, "bad side"); 
     if ((mBorderStyle[aSide] & BORDER_COLOR_SPECIAL) == 0)
       aColor = mBorderColor[aSide]; 
     else if (mBorderStyle[aSide] & BORDER_COLOR_FOREGROUND)
       aForeground = PR_TRUE;
     else
-      aTransparent = PR_TRUE;
+      NS_NOTREACHED("OUTLINE_COLOR_INITIAL should not be set here");
   }
 
   void SetBorderColor(PRUint8 aSide, nscolor aColor) 
@@ -541,10 +540,10 @@ struct nsStyleBorder {
       *aColors = mBorderColors[aIndex];
   }
 
-  void AppendBorderColor(PRInt32 aIndex, nscolor aColor, PRBool aTransparent)
+  void AppendBorderColor(PRInt32 aIndex, nscolor aColor)
   {
     NS_ASSERTION(aIndex >= 0 && aIndex <= 3, "bad side for composite border color");
-    nsBorderColors* colorEntry = new nsBorderColors(aColor, aTransparent);
+    nsBorderColors* colorEntry = new nsBorderColors(aColor);
     if (!mBorderColors[aIndex])
       mBorderColors[aIndex] = colorEntry;
     else {
@@ -556,13 +555,6 @@ struct nsStyleBorder {
     mBorderStyle[aIndex] &= ~BORDER_COLOR_SPECIAL;
   }
 
-  void SetBorderTransparent(PRUint8 aSide)
-  {
-    NS_ASSERTION(aSide <= NS_SIDE_LEFT, "bad side"); 
-    mBorderStyle[aSide] &= ~BORDER_COLOR_SPECIAL;
-    mBorderStyle[aSide] |= BORDER_COLOR_TRANSPARENT; 
-  }
-
   void SetBorderToForeground(PRUint8 aSide)
   {
     NS_ASSERTION(aSide <= NS_SIDE_LEFT, "bad side"); 
diff --git a/layout/style/nsStyleStructList.h b/layout/style/nsStyleStructList.h
index bb74695d2b94..0134de0133b1 100644
--- a/layout/style/nsStyleStructList.h
+++ b/layout/style/nsStyleStructList.h
@@ -76,7 +76,7 @@ STYLE_STRUCT_INHERITED(Color, CheckColorCallback, (SSARG_PRESCONTEXT))
   STYLE_STRUCT_TEST_CODE(      })
   STYLE_STRUCT_TEST_CODE(    } else {)
   STYLE_STRUCT_TEST_CODE(      if (STYLE_STRUCT_TEST == 2) {)
-STYLE_STRUCT_RESET(Background, nsnull, (SSARG_PRESCONTEXT))
+STYLE_STRUCT_RESET(Background, nsnull, ())
   STYLE_STRUCT_TEST_CODE(      } else {)
 STYLE_STRUCT_INHERITED(List, nsnull, ())
   STYLE_STRUCT_TEST_CODE(      })
diff --git a/layout/tables/nsTableFrame.cpp b/layout/tables/nsTableFrame.cpp
index 00d472e1a919..78b9e4e92b65 100644
--- a/layout/tables/nsTableFrame.cpp
+++ b/layout/tables/nsTableFrame.cpp
@@ -4575,12 +4575,9 @@ GetColorAndStyle(const nsIFrame*  aFrame,
       (NS_STYLE_BORDER_STYLE_HIDDEN == aStyle)) {
     return;
   }
-  PRBool transparent, foreground;
-  styleData->GetBorderColor(aSide, aColor, transparent, foreground);
-  if (transparent) { 
-    aColor = 0;
-  }
-  else if (foreground) {
+  PRBool foreground;
+  styleData->GetBorderColor(aSide, aColor, foreground);
+  if (foreground) {
     aColor = aFrame->GetStyleColor()->mColor;
   }
 }
diff --git a/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp b/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
index 0daded3af35f..5c609fc0b1ac 100644
--- a/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
+++ b/layout/xul/base/src/tree/src/nsTreeBodyFrame.cpp
@@ -3199,14 +3199,11 @@ nsTreeBodyFrame::PaintCell(PRInt32              aRowIndex,
 
       const nsStyleBorder* borderStyle = lineContext->GetStyleBorder();
       nscolor color;
-      PRBool transparent, foreground;
-      borderStyle->GetBorderColor(NS_SIDE_LEFT, color, transparent, foreground);
+      PRBool foreground;
+      borderStyle->GetBorderColor(NS_SIDE_LEFT, color, foreground);
       if (foreground) {
         // GetBorderColor didn't touch color, thus grab it from the treeline context
         color = lineContext->GetStyleColor()->mColor;
-      } else if (transparent) {
-        // GetBorderColor didn't touch color, thus set it to transparent
-        color = NS_RGBA(0, 0, 0, 0);
       }
       aRenderingContext.SetColor(color);
       PRUint8 style;