Are you annoyed by #Firefox's tab "buttons"? Would you like them to look like… tabs? Find your profile directory (probably something like ~/.mozilla/firefox/*.default/), there sholud be a chrome/ subdir. Create userChrome.css contaninig:@namespace html url("http://www.w3.org/1999/xhtml"); :root { --tab-border-radius: 4px 4px 0 0 !important; /* until version 153 */ --tab-block-margin: 4px 0 !important; /* from version 154 */ --tab-margin-block: 4px 0 !important; } .tab-background { border-color: lightgray !important; border-style: solid solid none solid !important; border-width: 1px !important; }and get actual tabs!