If you have the Plus Pack (Publisher or Pro account) with OptimizePress, you have some extra element styles for the Tabs element.

You may also be able to adapt the code below for other styles, but this code is for the Tabs Style 3 which is the 3rd option down when selecting the tabs element as you can see here:

Just add the below CSS into the live editor under “Page Settings > Other Scripts > Custom CSS” and grab some colors from colorpicker.com and see what you can come up with. You can change the tab’s background as well as the tab color and hover colors.