--- a/browser/themes/osx/browser.css
+++ b/browser/themes/osx/browser.css
@@ -1090,18 +1090,16 @@ toolbarbutton.chevron > .toolbarbutton-m
   margin: 0;
 }
 
 %include ../shared/tabs.inc.css
 
 .tab-label {
   margin-top: 1px;
   margin-bottom: 0;
-  -moz-box-flex: 1;
-  text-align: center;
 }
 
 .tabbrowser-tab:not(:hover) > .tab-stack > .tab-content > .tab-icon-image:not([selected="true"]) {
   opacity: .9;
 }
 
 /*
  * Force the overlay to create a new stacking context so it always appears on