--- a/browser/themes/osx/browser.css
+++ b/browser/themes/osx/browser.css
@@ -60,17 +60,17 @@
   display: -moz-box;
   height: 2px;
   margin-top: -2px;
   position: relative;
   z-index: 2; /* navbar is at 1 */
 }
 
 @media (-moz-mac-yosemite-theme) {
-  #navigator-toolbox::after {
+  #navigator-toolbox:-moz-window-inactive::after {
     background-image: linear-gradient(to top, hsla(0,0%,0%,.1), hsla(0,0%,0%,.1) 1px, hsla(0,0%,100%,0) 1px, hsla(0,0%,100%,0) 2px, transparent 3px);
   }
 }
 
 #navigator-toolbox toolbarbutton:-moz-lwtheme {
   color: inherit;
   text-shadow: inherit;
 }