Git clone this repo on your firefox profile, inside "chrome" directory, if not exists you will need create it.

The userChrome.css and userContent.css files works like an options\configurations file. All main "features" can be enabled and disabled there.

Edit userChrome.css and userContent.css with any text editor and enable or disable any feature you like by modifying, removing or outcommenting available @import strings. Restart Firefox after every modification for changes to take effect.