--- a/browser/themes/windows/browser-aero.css
+++ b/browser/themes/windows/browser-aero.css
@@ -316,21 +316,16 @@
   }
 
   #appcontent:not(:-moz-lwtheme) {
     background-color: -moz-dialog;
   }
 }
 
 @media (-moz-windows-glass) {
-  #main-window[sizemode=normal] #nav-bar {
-    border-top-left-radius: 2.5px;
-    border-top-right-radius: 2.5px;
-  }
-
   /* Set to full fill-opacity to improve visibility of toolbar buttons on aero glass. */
   #TabsToolbar:not(:-moz-lwtheme) {
     --toolbarbutton-icon-fill-opacity: 1;
   }
 
   #toolbar-menubar:not(:-moz-lwtheme) {
     text-shadow: 0 0 .5em white, 0 0 .5em white, 0 1px 0 rgba(255,255,255,.4);
   }