Add display:block to every absolutely positioned element

chrome/tabs_animated_gradient_border.css

@@ -13,7 +13,7 @@ Thanks to /u/skenera on reddit for suggesting animating background position and
 
 #TabsToolbar::before{
   content: "";
-  display: -moz-box;
+  display: block;
   position: absolute;
   width: 200vw;
   height: calc(var(--tab-min-height) + 2px);