This has nothing to do with Google Chrome.
You can’t actually add any features you can only modify what’s already there to change, hide, or move it. It allows you to change the appearance and layout of everything surrounding the webpage iteslf. While style sheets are normally applied to web pages, this particular style sheet is applied to Firefox’s user interface.
RELATED: Firefox Quantum Isn't Just 'Copying' Chrome: It's Much More Powerfulįirefox’s userChrome.css file is a cascading style sheet (CSS) file that Firefox uses.