Ellipsis will take up less space from Firefox 53 onwards: https://blog.nightly.mozilla.org/2016/12/20/these-weeks-in-firefox-issue-7/ https://blog.nightly.mozil

Ellipsis will take up less space from Firefox 53 onwards: https://blog.nightly.mozilla.org/2016/12/20/these-weeks-in-firefox-issue-7/ https://blog.nightly.mozilla.org/2016/12/20/these-weeks-in-f... As for the CSS-file, you have to create a folder called "chrome" in your profile folder and then in that folder create a file "userChrome.css". In that file, you have to have the following line at the top of everything else: "@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");" http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xu... From that point onwards, I'd just search on userstyles.org. In the advanced search, select "App" from the first dropdown, then it'll show you pretty much only Firefox-styles. If you found something that suites your taste, you can click the "Show CSS"-link and copy-paste that into userChrome.css. Just make sure that you don't have the @namespace-line twice. This for example sets the minimal tab-width rather low: https://userstyles.org/styles/53019/firefox-5-minimal-browser-tab-width https://userstyles.org/styles/53019/firefox-5-minimal-browse... You can also find userstyles that for example hide the close-button until you hover over the tab or merge the close-button with the favicon.