--- a/layout/style/nsRuleNode.cpp
+++ b/layout/style/nsRuleNode.cpp
@@ -3619,42 +3619,16 @@ nsRuleNode::SetFont(nsPresContext* aPres
       systemFont.weight = fontStyle.weight;
       systemFont.stretch = fontStyle.stretch;
       systemFont.size =
         NSFloatPixelsToAppUnits(fontStyle.size,
                                 aPresContext->DeviceContext()->
                                   AppUnitsPerDevPixelAtUnitFullZoom());
       //systemFont.langGroup = fontStyle.langGroup;
       systemFont.sizeAdjust = fontStyle.sizeAdjust;
-
-#ifdef XP_WIN
-      // XXXldb This platform-specific stuff should be in the
-      // LookAndFeel implementation, not here.
-      // XXXzw Should we even still *have* this code?  It looks to be making
-      // old, probably obsolete assumptions.
-
-      if (fontID == LookAndFeel::eFont_Field ||
-          fontID == LookAndFeel::eFont_Button ||
-          fontID == LookAndFeel::eFont_List) {
-        // As far as I can tell the system default fonts and sizes
-        // on MS-Windows for Buttons, Listboxes/Comboxes and Text Fields are
-        // all pre-determined and cannot be changed by either the control panel
-        // or programmatically.
-        // Fields (text fields)
-        // Button and Selects (listboxes/comboboxes)
-        //    We use whatever font is defined by the system. Which it appears
-        //    (and the assumption is) it is always a proportional font. Then we
-        //    always use 2 points smaller than what the browser has defined as
-        //    the default proportional font.
-        // Assumption: system defined font is proportional
-        systemFont.size =
-          std::max(defaultVariableFont->size -
-                 nsPresContext::CSSPointsToAppUnits(2), 0);
-      }
-#endif
     }
   }
 
   // font-family: font family list, enum, inherit
   const nsCSSValue* familyValue = aRuleData->ValueForFontFamily();
   NS_ASSERTION(eCSSUnit_Enumerated != familyValue->GetUnit(),
                "system fonts should not be in mFamily anymore");
   if (eCSSUnit_FontFamilyList == familyValue->GetUnit()) {

--- a/widget/windows/nsLookAndFeel.cpp
+++ b/widget/windows/nsLookAndFeel.cpp
@@ -617,16 +617,31 @@ GetSysFontInfo(HDC aHDC, LookAndFeel::Fo
 
   // we have problem on Simplified Chinese system because the system
   // report the default font size is 8 points. but if we use 8, the text
   // display very ugly. force it to be at 9 points (12 pixels) on that
   // system (cp936), but leave other sizes alone.
   if (pixelHeight < 12 && ::GetACP() == 936)
     pixelHeight = 12;
 
+  if (anID == LookAndFeel::eFont_Field ||
+      anID == LookAndFeel::eFont_Button ||
+      anID == LookAndFeel::eFont_List) {
+    // As far as I can tell the system default fonts and sizes
+    // on MS-Windows for Buttons, Listboxes/Comboxes and Text Fields are
+    // all pre-determined and cannot be changed by either the control panel
+    // or programmatically.
+    // Fields (text fields)
+    // Button and Selects (listboxes/comboboxes)
+    // We use whatever font is defined by the system, but explicitly use
+    // 10 points (13.33px) for consistency with our existing default behavior
+    // as well as other browsers on Windows.
+    pixelHeight = 96.0f / 72.0f * 10;
+  }
+
   aFontStyle.size = pixelHeight;
 
   // FIXME: What about oblique?
   aFontStyle.style =
     (ptrLogFont->lfItalic) ? NS_FONT_STYLE_ITALIC : NS_FONT_STYLE_NORMAL;
 
   // FIXME: Other weights?
   aFontStyle.weight =