--- a/browser/themes/windows/browser.css
+++ b/browser/themes/windows/browser.css
@@ -1187,16 +1187,21 @@ toolbarbutton[constrain-size="true"][cui
   background-clip: padding-box;
   border: 1px solid ThreeDShadow;
 }
 
 #urlbar {
   -moz-padding-end: 2px;
 }
 
+/* overlap the urlbar's border */
+#PopupAutoCompleteRichResult {
+  margin-top: -1px;
+}
+
 @media (-moz-os-version: windows-xp),
        (-moz-os-version: windows-vista),
        (-moz-os-version: windows-win7) {
   #urlbar,
   .searchbar-textbox {
     border-radius: 2px;
   }
 }
@@ -1230,16 +1235,21 @@ toolbarbutton[constrain-size="true"][cui
     .searchbar-textbox:not(:-moz-lwtheme):hover {
       border-color: hsl(0,0%,80%);
     }
 
     #urlbar:not(:-moz-lwtheme)[focused],
     .searchbar-textbox:not(:-moz-lwtheme)[focused] {
       box-shadow: 0 0 0 1px Highlight inset;
     }
+
+    /* overlap the urlbar's border and inset box-shadow */
+    #PopupAutoCompleteRichResult:not(:-moz-lwtheme) {
+      margin-top: -2px;
+    }
   }
 
   @media not all and (-moz-os-version: windows-xp) {
     #urlbar:not(:-moz-lwtheme)[focused],
     .searchbar-textbox:not(:-moz-lwtheme)[focused] {
       border-color: Highlight;
     }
   }