diff --git a/content/html/style/src/nsCSSStyleRule.cpp b/content/html/style/src/nsCSSStyleRule.cpp
index e2917cc62d4b..7eb2e08fd41f 100644
--- a/content/html/style/src/nsCSSStyleRule.cpp
+++ b/content/html/style/src/nsCSSStyleRule.cpp
@@ -589,20 +589,23 @@ void CSSStyleRuleImpl::MapStyleInto(nsIStyleContext* aContext, nsIPresContext* a
 
           const nsFont& normal = aPresContext->GetDefaultFont();
           const nsFont& normalFixed = aPresContext->GetDefaultFixedFont();
+          PRInt32 scaler = aPresContext->GetFontScaler();
+          float scaleFactor = nsStyleUtil::GetScalingFactor(scaler);
+
           if ((NS_STYLE_FONT_SIZE_XXSMALL <= value) && 
               (value <= NS_STYLE_FONT_SIZE_XXLARGE)) {
-            font->mFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normal.size);
-            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normalFixed.size);
+            font->mFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normal.size, scaleFactor);
+            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normalFixed.size, scaleFactor);
           }
           else if (NS_STYLE_FONT_SIZE_LARGER == value) {
-            PRInt32 index = nsStyleUtil::FindNextLargerFontSize(parentFont->mFont.size, (PRInt32)normal.size);
-            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size);
-            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size);
+            PRInt32 index = nsStyleUtil::FindNextLargerFontSize(parentFont->mFont.size, (PRInt32)normal.size, scaleFactor);
+            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size, scaleFactor);
+            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size, scaleFactor);
           }
           else if (NS_STYLE_FONT_SIZE_SMALLER == value) {
-            PRInt32 index = nsStyleUtil::FindNextSmallerFontSize(parentFont->mFont.size, (PRInt32)normal.size);
-            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size);
-            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size);
+            PRInt32 index = nsStyleUtil::FindNextSmallerFontSize(parentFont->mFont.size, (PRInt32)normal.size, scaleFactor);
+            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size, scaleFactor);
+            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size, scaleFactor);
           }
           // this does NOT explicitly set font size
         }
diff --git a/content/html/style/src/nsStyleUtil.cpp b/content/html/style/src/nsStyleUtil.cpp
index 7a09a40b7874..50e443f4b255 100644
--- a/content/html/style/src/nsStyleUtil.cpp
+++ b/content/html/style/src/nsStyleUtil.cpp
@@ -21,7 +21,41 @@
 #include "nsIStyleContext.h"
 #include "nsStyleConsts.h"
 
-nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize)
+#define POSITIVE_SCALE_FACTOR 1.10 /* 10% */
+#define NEGATIVE_SCALE_FACTOR .90  /* 10% */
+
+/*
+ * Return the scaling percentage given a font scaler
+ * Lifted from layutil.c
+ */
+float nsStyleUtil::GetScalingFactor(PRInt32 aScaler)
+{
+  double scale = 1.0;
+  double mult;
+  PRInt32 count;
+
+  if(aScaler < 0)   {
+    count = -aScaler;
+    mult = NEGATIVE_SCALE_FACTOR;
+  }
+  else {
+    count = aScaler;
+    mult = POSITIVE_SCALE_FACTOR;
+  }
+
+  /* use the percentage scaling factor to the power of the pref */
+  while(count--) {
+    scale *= mult;
+  }
+
+  return scale;
+}
+
+/*
+ * Lifted from winfe/cxdc.cpp
+ */
+nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize,
+                                       float aScalingFactor)
 { // lifted directly from Nav 5.0 code to replicate rounding errors
   double dFontSize;
 
@@ -54,23 +88,28 @@ nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize
 	default:
 		dFontSize = aBasePointSize;
 	}
+
+  dFontSize *= aScalingFactor;
+
   return (nscoord)dFontSize;
 }
 
-PRInt32 nsStyleUtil::FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize)
+PRInt32 nsStyleUtil::FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                             float aScalingFactor)
 {
   PRInt32 index;
   for (index = 7; index > 1; index--)
-    if (aFontSize > nsStyleUtil::CalcFontPointSize(index, aBasePointSize))
+    if (aFontSize > nsStyleUtil::CalcFontPointSize(index, aBasePointSize, aScalingFactor))
       break;
   return index;
 }
 
-PRInt32 nsStyleUtil::FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize)
+PRInt32 nsStyleUtil::FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                            float aScalingFactor)
 {
   PRInt32 index;
   for (index = 1; index < 7; index++)
-    if (aFontSize < nsStyleUtil::CalcFontPointSize(index, aBasePointSize))
+    if (aFontSize < nsStyleUtil::CalcFontPointSize(index, aBasePointSize, aScalingFactor))
       break;
   return index;
 }
diff --git a/content/shared/src/nsStyleUtil.cpp b/content/shared/src/nsStyleUtil.cpp
index 7a09a40b7874..50e443f4b255 100644
--- a/content/shared/src/nsStyleUtil.cpp
+++ b/content/shared/src/nsStyleUtil.cpp
@@ -21,7 +21,41 @@
 #include "nsIStyleContext.h"
 #include "nsStyleConsts.h"
 
-nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize)
+#define POSITIVE_SCALE_FACTOR 1.10 /* 10% */
+#define NEGATIVE_SCALE_FACTOR .90  /* 10% */
+
+/*
+ * Return the scaling percentage given a font scaler
+ * Lifted from layutil.c
+ */
+float nsStyleUtil::GetScalingFactor(PRInt32 aScaler)
+{
+  double scale = 1.0;
+  double mult;
+  PRInt32 count;
+
+  if(aScaler < 0)   {
+    count = -aScaler;
+    mult = NEGATIVE_SCALE_FACTOR;
+  }
+  else {
+    count = aScaler;
+    mult = POSITIVE_SCALE_FACTOR;
+  }
+
+  /* use the percentage scaling factor to the power of the pref */
+  while(count--) {
+    scale *= mult;
+  }
+
+  return scale;
+}
+
+/*
+ * Lifted from winfe/cxdc.cpp
+ */
+nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize,
+                                       float aScalingFactor)
 { // lifted directly from Nav 5.0 code to replicate rounding errors
   double dFontSize;
 
@@ -54,23 +88,28 @@ nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize
 	default:
 		dFontSize = aBasePointSize;
 	}
+
+  dFontSize *= aScalingFactor;
+
   return (nscoord)dFontSize;
 }
 
-PRInt32 nsStyleUtil::FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize)
+PRInt32 nsStyleUtil::FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                             float aScalingFactor)
 {
   PRInt32 index;
   for (index = 7; index > 1; index--)
-    if (aFontSize > nsStyleUtil::CalcFontPointSize(index, aBasePointSize))
+    if (aFontSize > nsStyleUtil::CalcFontPointSize(index, aBasePointSize, aScalingFactor))
       break;
   return index;
 }
 
-PRInt32 nsStyleUtil::FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize)
+PRInt32 nsStyleUtil::FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                            float aScalingFactor)
 {
   PRInt32 index;
   for (index = 1; index < 7; index++)
-    if (aFontSize < nsStyleUtil::CalcFontPointSize(index, aBasePointSize))
+    if (aFontSize < nsStyleUtil::CalcFontPointSize(index, aBasePointSize, aScalingFactor))
       break;
   return index;
 }
diff --git a/layout/html/forms/src/nsInputButton.cpp b/layout/html/forms/src/nsInputButton.cpp
index 6256c3706da7..c658af8fb337 100644
--- a/layout/html/forms/src/nsInputButton.cpp
+++ b/layout/html/forms/src/nsInputButton.cpp
@@ -569,8 +569,10 @@ nsInputButtonFrame::PostCreateWidget(nsIPresContext* aPresContext, nsIView *aVie
         widgetFont.name = "Arail";  // XXX windows specific font
         widgetFont.weight = NS_FONT_WEIGHT_NORMAL; 
         const nsFont& normal = aPresContext->GetDefaultFont();
-        PRInt32 fontIndex = nsStyleUtil::FindNextSmallerFontSize(widgetFont.size, (PRInt32)normal.size);
-        widgetFont.size = nsStyleUtil::CalcFontPointSize(fontIndex, (PRInt32)normal.size);
+        PRInt32 scaler = aPresContext->GetFontScaler();
+        float scaleFactor = nsStyleUtil::GetScalingFactor(scaler);
+        PRInt32 fontIndex = nsStyleUtil::FindNextSmallerFontSize(widgetFont.size, (PRInt32)normal.size, scaleFactor);
+        widgetFont.size = nsStyleUtil::CalcFontPointSize(fontIndex, (PRInt32)normal.size, scaleFactor);
         button->SetFont(widgetFont);
       }
     }
diff --git a/layout/html/forms/src/nsSelect.cpp b/layout/html/forms/src/nsSelect.cpp
index eb17bd4fff8a..b911c8e09d51 100644
--- a/layout/html/forms/src/nsSelect.cpp
+++ b/layout/html/forms/src/nsSelect.cpp
@@ -337,8 +337,10 @@ nsSelectFrame::PostCreateWidget(nsIPresContext* aPresContext, nsIView *aView)
     widgetFont.name = "Arail";  // XXX windows specific font
     widgetFont.weight = NS_FONT_WEIGHT_NORMAL; 
     const nsFont& normal = aPresContext->GetDefaultFont();
-    PRInt32 fontIndex = nsStyleUtil::FindNextSmallerFontSize(widgetFont.size, (PRInt32)normal.size);
-    widgetFont.size = nsStyleUtil::CalcFontPointSize(fontIndex, (PRInt32)normal.size);
+    PRInt32 scaler = aPresContext->GetFontScaler();
+    float scaleFactor = nsStyleUtil::GetScalingFactor(scaler);
+    PRInt32 fontIndex = nsStyleUtil::FindNextSmallerFontSize(widgetFont.size, (PRInt32)normal.size, scaleFactor);
+    widgetFont.size = nsStyleUtil::CalcFontPointSize(fontIndex, (PRInt32)normal.size, scaleFactor);
     list->SetFont(widgetFont);
   }
 
diff --git a/layout/html/style/public/nsStyleUtil.h b/layout/html/style/public/nsStyleUtil.h
index 75a750cf7b0c..45e7ac116424 100644
--- a/layout/html/style/public/nsStyleUtil.h
+++ b/layout/html/style/public/nsStyleUtil.h
@@ -27,10 +27,15 @@ struct nsStyleColor;
 // Style utility functions
 class nsStyleUtil {
 public:
+  
+  static float GetScalingFactor(PRInt32 aScaler);
 
-  static nscoord CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize);
-  static PRInt32 FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize);
-  static PRInt32 FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize);
+  static nscoord CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize, 
+                                   float aScalingFactor);
+  static PRInt32 FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                         float aScalingFactor);
+  static PRInt32 FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                        float aScalingFactor);
 
   static const nsStyleColor* FindNonTransparentBackground(nsIStyleContext* aContext);
 };
diff --git a/layout/html/style/src/nsCSSStyleRule.cpp b/layout/html/style/src/nsCSSStyleRule.cpp
index e2917cc62d4b..7eb2e08fd41f 100644
--- a/layout/html/style/src/nsCSSStyleRule.cpp
+++ b/layout/html/style/src/nsCSSStyleRule.cpp
@@ -589,20 +589,23 @@ void CSSStyleRuleImpl::MapStyleInto(nsIStyleContext* aContext, nsIPresContext* a
 
           const nsFont& normal = aPresContext->GetDefaultFont();
           const nsFont& normalFixed = aPresContext->GetDefaultFixedFont();
+          PRInt32 scaler = aPresContext->GetFontScaler();
+          float scaleFactor = nsStyleUtil::GetScalingFactor(scaler);
+
           if ((NS_STYLE_FONT_SIZE_XXSMALL <= value) && 
               (value <= NS_STYLE_FONT_SIZE_XXLARGE)) {
-            font->mFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normal.size);
-            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normalFixed.size);
+            font->mFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normal.size, scaleFactor);
+            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normalFixed.size, scaleFactor);
           }
           else if (NS_STYLE_FONT_SIZE_LARGER == value) {
-            PRInt32 index = nsStyleUtil::FindNextLargerFontSize(parentFont->mFont.size, (PRInt32)normal.size);
-            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size);
-            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size);
+            PRInt32 index = nsStyleUtil::FindNextLargerFontSize(parentFont->mFont.size, (PRInt32)normal.size, scaleFactor);
+            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size, scaleFactor);
+            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size, scaleFactor);
           }
           else if (NS_STYLE_FONT_SIZE_SMALLER == value) {
-            PRInt32 index = nsStyleUtil::FindNextSmallerFontSize(parentFont->mFont.size, (PRInt32)normal.size);
-            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size);
-            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size);
+            PRInt32 index = nsStyleUtil::FindNextSmallerFontSize(parentFont->mFont.size, (PRInt32)normal.size, scaleFactor);
+            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size, scaleFactor);
+            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size, scaleFactor);
           }
           // this does NOT explicitly set font size
         }
diff --git a/layout/html/style/src/nsStyleUtil.cpp b/layout/html/style/src/nsStyleUtil.cpp
index 7a09a40b7874..50e443f4b255 100644
--- a/layout/html/style/src/nsStyleUtil.cpp
+++ b/layout/html/style/src/nsStyleUtil.cpp
@@ -21,7 +21,41 @@
 #include "nsIStyleContext.h"
 #include "nsStyleConsts.h"
 
-nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize)
+#define POSITIVE_SCALE_FACTOR 1.10 /* 10% */
+#define NEGATIVE_SCALE_FACTOR .90  /* 10% */
+
+/*
+ * Return the scaling percentage given a font scaler
+ * Lifted from layutil.c
+ */
+float nsStyleUtil::GetScalingFactor(PRInt32 aScaler)
+{
+  double scale = 1.0;
+  double mult;
+  PRInt32 count;
+
+  if(aScaler < 0)   {
+    count = -aScaler;
+    mult = NEGATIVE_SCALE_FACTOR;
+  }
+  else {
+    count = aScaler;
+    mult = POSITIVE_SCALE_FACTOR;
+  }
+
+  /* use the percentage scaling factor to the power of the pref */
+  while(count--) {
+    scale *= mult;
+  }
+
+  return scale;
+}
+
+/*
+ * Lifted from winfe/cxdc.cpp
+ */
+nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize,
+                                       float aScalingFactor)
 { // lifted directly from Nav 5.0 code to replicate rounding errors
   double dFontSize;
 
@@ -54,23 +88,28 @@ nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize
 	default:
 		dFontSize = aBasePointSize;
 	}
+
+  dFontSize *= aScalingFactor;
+
   return (nscoord)dFontSize;
 }
 
-PRInt32 nsStyleUtil::FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize)
+PRInt32 nsStyleUtil::FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                             float aScalingFactor)
 {
   PRInt32 index;
   for (index = 7; index > 1; index--)
-    if (aFontSize > nsStyleUtil::CalcFontPointSize(index, aBasePointSize))
+    if (aFontSize > nsStyleUtil::CalcFontPointSize(index, aBasePointSize, aScalingFactor))
       break;
   return index;
 }
 
-PRInt32 nsStyleUtil::FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize)
+PRInt32 nsStyleUtil::FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                            float aScalingFactor)
 {
   PRInt32 index;
   for (index = 1; index < 7; index++)
-    if (aFontSize < nsStyleUtil::CalcFontPointSize(index, aBasePointSize))
+    if (aFontSize < nsStyleUtil::CalcFontPointSize(index, aBasePointSize, aScalingFactor))
       break;
   return index;
 }
diff --git a/layout/style/nsCSSStyleRule.cpp b/layout/style/nsCSSStyleRule.cpp
index e2917cc62d4b..7eb2e08fd41f 100644
--- a/layout/style/nsCSSStyleRule.cpp
+++ b/layout/style/nsCSSStyleRule.cpp
@@ -589,20 +589,23 @@ void CSSStyleRuleImpl::MapStyleInto(nsIStyleContext* aContext, nsIPresContext* a
 
           const nsFont& normal = aPresContext->GetDefaultFont();
           const nsFont& normalFixed = aPresContext->GetDefaultFixedFont();
+          PRInt32 scaler = aPresContext->GetFontScaler();
+          float scaleFactor = nsStyleUtil::GetScalingFactor(scaler);
+
           if ((NS_STYLE_FONT_SIZE_XXSMALL <= value) && 
               (value <= NS_STYLE_FONT_SIZE_XXLARGE)) {
-            font->mFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normal.size);
-            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normalFixed.size);
+            font->mFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normal.size, scaleFactor);
+            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(value + 1, (PRInt32)normalFixed.size, scaleFactor);
           }
           else if (NS_STYLE_FONT_SIZE_LARGER == value) {
-            PRInt32 index = nsStyleUtil::FindNextLargerFontSize(parentFont->mFont.size, (PRInt32)normal.size);
-            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size);
-            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size);
+            PRInt32 index = nsStyleUtil::FindNextLargerFontSize(parentFont->mFont.size, (PRInt32)normal.size, scaleFactor);
+            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size, scaleFactor);
+            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size, scaleFactor);
           }
           else if (NS_STYLE_FONT_SIZE_SMALLER == value) {
-            PRInt32 index = nsStyleUtil::FindNextSmallerFontSize(parentFont->mFont.size, (PRInt32)normal.size);
-            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size);
-            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size);
+            PRInt32 index = nsStyleUtil::FindNextSmallerFontSize(parentFont->mFont.size, (PRInt32)normal.size, scaleFactor);
+            font->mFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normal.size, scaleFactor);
+            font->mFixedFont.size = nsStyleUtil::CalcFontPointSize(index, (PRInt32)normalFixed.size, scaleFactor);
           }
           // this does NOT explicitly set font size
         }
diff --git a/layout/style/nsStyleUtil.cpp b/layout/style/nsStyleUtil.cpp
index 7a09a40b7874..50e443f4b255 100644
--- a/layout/style/nsStyleUtil.cpp
+++ b/layout/style/nsStyleUtil.cpp
@@ -21,7 +21,41 @@
 #include "nsIStyleContext.h"
 #include "nsStyleConsts.h"
 
-nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize)
+#define POSITIVE_SCALE_FACTOR 1.10 /* 10% */
+#define NEGATIVE_SCALE_FACTOR .90  /* 10% */
+
+/*
+ * Return the scaling percentage given a font scaler
+ * Lifted from layutil.c
+ */
+float nsStyleUtil::GetScalingFactor(PRInt32 aScaler)
+{
+  double scale = 1.0;
+  double mult;
+  PRInt32 count;
+
+  if(aScaler < 0)   {
+    count = -aScaler;
+    mult = NEGATIVE_SCALE_FACTOR;
+  }
+  else {
+    count = aScaler;
+    mult = POSITIVE_SCALE_FACTOR;
+  }
+
+  /* use the percentage scaling factor to the power of the pref */
+  while(count--) {
+    scale *= mult;
+  }
+
+  return scale;
+}
+
+/*
+ * Lifted from winfe/cxdc.cpp
+ */
+nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize,
+                                       float aScalingFactor)
 { // lifted directly from Nav 5.0 code to replicate rounding errors
   double dFontSize;
 
@@ -54,23 +88,28 @@ nscoord nsStyleUtil::CalcFontPointSize(PRInt32 aHTMLSize, PRInt32 aBasePointSize
 	default:
 		dFontSize = aBasePointSize;
 	}
+
+  dFontSize *= aScalingFactor;
+
   return (nscoord)dFontSize;
 }
 
-PRInt32 nsStyleUtil::FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize)
+PRInt32 nsStyleUtil::FindNextSmallerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                             float aScalingFactor)
 {
   PRInt32 index;
   for (index = 7; index > 1; index--)
-    if (aFontSize > nsStyleUtil::CalcFontPointSize(index, aBasePointSize))
+    if (aFontSize > nsStyleUtil::CalcFontPointSize(index, aBasePointSize, aScalingFactor))
       break;
   return index;
 }
 
-PRInt32 nsStyleUtil::FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize)
+PRInt32 nsStyleUtil::FindNextLargerFontSize(nscoord aFontSize, PRInt32 aBasePointSize, 
+                                            float aScalingFactor)
 {
   PRInt32 index;
   for (index = 1; index < 7; index++)
-    if (aFontSize < nsStyleUtil::CalcFontPointSize(index, aBasePointSize))
+    if (aFontSize < nsStyleUtil::CalcFontPointSize(index, aBasePointSize, aScalingFactor))
       break;
   return index;
 }