Style tabs

In DO 13 I have several styles tabs and all the tabs seem to blend together because there is no strong outline on each tab. Is there a way to bold the outlines of the tabs or add some shading so they are more distinct from each other?

Those use the colors here:

Preferences / Colors and Fonts / Directory Opus Colors / [Other Colors] Folder tabs

(Folder Tabs also use those colors, of course.)

thanks. That helped a lot!