User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:89.0) Gecko/20100101 Firefox/89.0

Steps to reproduce:

The distinction between the active tab and inactive tabs is visually unclear. Since upgrading to 89 this has been an issue for me personally. Please see the attached screenshot. There is only a slightly shaded rectangle around the active tab and no other visual cues.

This occurs on my desktop and could be the result of the theme on my X window manager, but there are no other places that I have detected where GUI elements are rendered ambiguous by the default theme that I'm using. I am using Xfce with the "Default-xhdpi" theme on Debian Bullseye.

I would suggest making the active tab more visually distinct.

The Bugbug bot thinks this bug should belong to the 'Firefox::Theme' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.