How do I get rid of this gap in the tabs?

[David_H23]

I used to have a userChrome.css file that got rid of the gap at the top right of the browser between the "Open a new tab" button and "Minimize" button. After updating to Firefox 155.0.1 from Firefox 154.0.1 today, however, it changed it so the gap is back. The CSS I used to get rid of the gap no longer works. Any other CSS I've found online to get rid of the space doesn't work for me either. All other CSS I have does seem to still work for me, just not this.

The screenshot above is what it looked like before the update. There wasn't any gap between the "Open a new tab" (or +) and "Minimize" (or -) buttons.

The screenshot above shows what it now looks like. It's just unnecessary unused space. How do I get rid of the gap now, whether through CSS or a setting or something else?

[David_H23 · Accepted solution]

So I seemed to have fixed this issue by opening the "Customize Toolbar" page and dragging the space between the "Open a new tab" and "Minimize" buttons to the overflow menu. The gap is no longer there. I'm glad it appears to be fixed now, but I still don't know why Mozilla decided to randomly make the change that caused the CSS that gets rid of the gap to no longer work anymore in the first place.