GitLab

You’ll also want to add…

* {
	scrollbar-color:unset !important;
	scrollbar-width:unset !important;
}

… to your #Firefox chrome/userContent.css (see http://web.archive.org/web/20200922175950/https://support.mozilla.org/en-US/questions/1291465#answer-1324670 or https://www.userchrome.org/firefox-changes-userchrome-css.html#fx69 first though) to make Twitter, StackOverflow, etc. use reasonable scrollbars.