Multiple CSS fixes required for FF >= 67

[numirias]

In Firefox Nightly 67.0a1, the UI CSS is partially broken.

Notably:

• The tab label jumps when reloading a site
• Tab widths are fixed (don't shrink)
• Hovering over a tab causes the tab bar to jump

[Atavic]

I just want to 👍 for your efforts and I want to add that I'm going to use forks and not going to update FF (I am on ESR), due to this issue and many others similar ones.

[olaims]

I just can confirm the problems which @numirias described

edit: it happens on the 660b4 too

[numirias]

Thanks for the feedback to both of you!

The problems are patched in the new releases (3.x). But note they only work for FF >= 67, which is currently only available via Nightly. If you're not there yet, you'll need to use an older release.

Also note that I dropped some features as explained in #33.

Feel free to reopen if the bugs still occur.