"Clipped" corner when hovering over non-active tag adjactent to selected tag

[mitchdotnet]

Firstly, yes, I tweaked the corner radius and colors a bit, but this issue was present before I did any of that. When the mouse is hovered over the tag to the immediate left of the currently selected tag, the bottom-right corner is "clipped":

Installing this theme is my first time messing with Firefox's CSS at all so I'm not familiar with it enough to know where to look to try to solve this.

[OfficialFreak]

What's showing up for you is the pseudo element im using to "fake" the outward border radius. This should normally be hidden behind the neighboring tabs by setting the z-index to a low value. Im guessing something broke in the process of modifying the theme so I'd suggest doing a git diff to see what's changed and if that doesn't help, sending it here so I can take a look at it. :)

[mitchdotnet]

As mentioned I'm getting the same result with no modifications to userChrome.css:

[OfficialFreak]

Ah okay, it seems some outside factor is responsible then. I'm guessing you don't have another userChrome active which could interfere so the only things that could be different are Firefox Version and Operating System. I cannot reproduce the issue myself and the only solution I can think of right now is for you to use the Firefox Browser Devtools to try and play around with the z-index values of the tabs / position to figure out what's going wrong.