This may help

https://www.reddit.com/r/firefox/comments/1uiq1u/is_there_a_way_to_disable_tab_scrolling/

Try this code in userChrome.css

• https://github.com/MrOtherGuy/firefox-csshacks/blob/master/chrome/multi-row_tabs.css

See also:

• https://www.userchrome.org/what-is-userchrome-css.html
• https://www.userchrome.org/how-create-userchrome-css.html

In Firefox 69 and later you need to set this pref to true on the about:config page to enable userChrome.css and userContent.css in the chrome folder.

• toolkit.legacyUserProfileCustomizations.stylesheets = true

See:

• https://www.userchrome.org/firefox-changes-userchrome-css.html

dsa65 said

I hate it! I've tried changing tab size to '0' and a couple of CSS tweaks, but it's still there.

The browser.tabs.tabMinWidth preference can be lowered from 76 to 50 or lower, but the minimum actually implemented through that preference is 50 pixels.

What did you try in the way of CSS tweaks? The rules for letting tabs become as narrow as Chrome tabs aren't complicated, so the problem usually is one of the following:

• chrome folder not located in the exactly correct place
• userChrome.css file not named exactly correctly
• in Firefox 69+, didn't set Firefox to look for userChrome.css at startup in about:config

To double-check on those steps, see: https://www.userchrome.org/how-create-userchrome-css.html