What would cause the tabs to be 'stacked' on top of each other and go the full width of the center column?

I've tried uploading a fresh copy of the tab css that I'm using (w/o any changes) and the tabs are still stacked.

I've upload fresh copies of the files and still nothing is fixed

I've checked and rechecked that they work correctly and they do. That is why I heavily favor a css error is at large here.

Any suggestions....