User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:57.0) Gecko/20100101 Firefox/57.0 Build ID: 20170913220121 Steps to reproduce: Open enough tabs that the center of the title bar has a tab behind it. Actual results: A barely-legible page title overlays the tabs. It prevents clicking on the top 3/4 of the tab and doesn't look very good. Expected results: I wouldn't expect the overlay title to be there at all, since it's already in the focused tab.