[Dusseldorf]

I finally got frustrated enough to go in and manually increase the default scrollbar size in Firefox. Slim scrollbars are awful both to look at and to use. I'm working with an ultrawide monitor here, please give me more than 0-3 pixels of scrollbar!

[recursive]

I didn't know this was possible. This is amazing! I found it under the inconspicuous config item called "widget.non-native-theme.scrollbar.style". I changed it from 0 to 4. There seems to be no UI for this.

Source: https://support.mozilla.org/en-US/questions/1443060