I cannot understand why Firefox refuses to make this a standard option.
Anyway, the full instructions are in the description of this video.
1. Find your FF profile folder (location is in about:support if you don’t know it)
2. Navigate to the Chrome sub-folder (or make one if there is none)
3. Create a file called userchrome.css with this content:
/* Source file https://github.com/MrOtherGuy/firefox-csshacks/tree/master/chrome/multi-row_tabs.css made available under Mozilla Public License v. 2.0 See the above repository for updates as well as full license text. */ /* Makes tabs to appear on multiple lines */ /* Tab reordering will not work and can't be made to work */ /* You can use multi-row_tabs_window_control_patch.css to move window controls to nav-bar*/ /* You might want to move tabs-new-tab-button outside tabs toolbar for smoother behavior */ /* Change the --multirow-n-rows to change maximum number of rows before the rows will start to scroll */ :root{ --multirow-n-rows: 3; --multirow-tab-min-width: 100px; --multirow-tab-dynamic-width: 1; /* Change to 0 for fixed-width tabs using the above width. */ } /* Scrollbar can't be clicked but the rows can be scrolled with mouse wheel */ /* Uncomment the next line if you want to be able to use the scrollbar with mouse clicks */ /* #tabbrowser-arrowscrollbox{ -moz-window-dragging: no-drag } */ /* Uncommenting the above makes you unable to drag the window from empty space in the tab strip but normal draggable spaces will continue to work */ #tabbrowser-tabs{ min-height: unset !important; padding-inline-start: 0px !important } @-moz-document url(chrome://browser/content/browser.xhtml){ #scrollbutton-up~spacer, #scrollbutton-up, #scrollbutton-down{ display: var(--scrollbutton-display-model,initial) } scrollbox[part][orient="horizontal"]{ display: flex; flex-wrap: wrap; overflow-y: auto; max-height: calc(var(--tab-min-height) * var(--multirow-n-rows)); scrollbar-color: currentColor transparent; scrollbar-width: thin; } } .scrollbox-clip[orient="horizontal"], #tabbrowser-arrowscrollbox{ overflow: -moz-hidden-unscrollable; display: block; --scrollbutton-display-model: none; } .tabbrowser-tab{ height: var(--tab-min-height); } #tabbrowser-tabs .tabbrowser-tab[pinned]{ position: static !important; margin-inline-start: 0px !important; } .tabbrowser-tab[fadein]:not([pinned]){ min-width: var(--multirow-tab-min-width) !important; flex-grow: var(--multirow-tab-dynamic-width); /*
- Go to about:config and search for toolkit.legacyUserProfileCustomizations
- Toggle it to true
- exit and restart firefox
Worked for me!