Clone the repo

Copy (?) the contents of current into `your_firefox_profile/chrome`

Turn on multi-row tabs (`css/tabs/tabs_multiple_lines.css`) in `userChrome.css`, and leave `@import “./config/general_variables.css”;` enabled – you probably want to turn off everything else (replace \n@import with \n\/\*@import) because it looks janky

Increase the number of tab lines in general_variables.css (`tabs-lines`)