I warn you that I tried using the module linked to above, and it can be quite tough to get it to do what you want (for example, only format the tab part without the rest of the page background). In addition, keep in mind that you need to set fixed width and height for the tabs on the form (not 0"), otherwise the module won't work at all. Overall, I think it's more trouble than it's worth, but if you're really intent on doing it, it's worth a shot.