reverse tab-background direction so context-line shows at bottom

chrome/curved_tabs.css

@@ -56,6 +56,8 @@ See the above repository for updates as well as full license text. */
   transform: scaleX(-1);
 }
 
+.tab-background{ -moz-box-direction: reverse }
+
 .tabbrowser-tab:hover > stack > .tab-background,
 .tab-background[selected]{
   border-radius: var(--uc-tab-curve-size) var(--uc-tab-curve-size) 0 0 !important;