Fix the look of tab groups

This is a style request. In my everyday work, I use group tabs quite often. I always see a missed pixel at the bottom left corner when I name a group.

I would appreciate it if you could fix this styling bug.

I’m using Version 1.30.76 Chromium: 93.0.4577.82 (Official Build) beta (64-bit)on popOS.

Thank you for your hard work.