As bovine3dom has mentioned already, b is the default keybind. For userChrome, I use https://github.com/MrOtherGuy/firefox-csshacks/blob/master/chrome/hide_tab

As bovine3dom has mentioned already, b is the default keybind. For userChrome, I use https://github.com/MrOtherGuy/firefox-csshacks/blob/master/chrome/hide_tabs_toolbar.css https://github.com/MrOtherGuy/firefox-csshacks/blob/master/c... Not my GitHub, but incredibly useful repo for all kinds of userChrome shenanigans. Personally I keep it to a minimum (literally just this hack) so that I have less stuff to look at if an update breaks something.