Consider having just two of them. The one which is active actually seems like a button that demands attention. It's basic design stuff. Tabs denote choices between active viewports, it should be unambiguous always which one is active. These hovering tabs are more like buttons which intuitively ask to be clicked

https://github.com/black7375/Firefox-UI-Fix

Try looking at the comparison screenshots in this repo. Or look up some images of firefox australis. You'll see how tabs are actually behaving like tabs and are denoting clearly which one is active by linking itself naturally to the viewport

Edit: https://github.com/Glitchcode2447/Firefox-Australis-Theme