It's fixed, but the same happens when not fixed. As soon as you narrow the browser to where they should break down to become on a lower line, the overlap for a bit until you reduce the width more then finally go down
It is the Widget Framework Sidebar causing this. Remove that and it works as expected.
Odd though it should happen even when the sidebar leaves enough room. It is stopping the tabs from floating correctly so I guess it's a bug in Widget framework