Board Thread:Support Requests - Getting Technical/@comment-4503522-20151205182736/@comment-4731443-20151205204953

Targeting the anchors instead should fill the whole tabs:

.selector .tabbernav li:nth-of-type(1) a { background-color: blue; } .selector .tabbernav li:nth-of-type(2) a { background-color: orange; } etc.

If the color goes past your rounded corners, use  with the declaration that sets the border-radius.