Broken ellipsis behaviour for in-page nav component fix

Fixed the broken ellipsis behaviour back to work so if the tab title is too long for the given space, crop and replace part of the text to ellipsis.

This fix uses :only-of-type css selector instead of using any javascript assist, which means it will not work on IE8. But this fix is mainly for mobile browsers and newer browsers that support media queries so it shouldn't be a problem.