Hi! I want to edit system theme for firefox. Where exactly is it stored on the disk? Previously it is asked here: https://support.mozilla.org/en-US/questions/940165 But that answer does not reveal the exact file location. For example if I want to tweak font used on browser tab or shadow color around browser tab what exactly do I have to edit? PS I dont want simply to customize colors like themes you can find on the internet do. I want to customize entire html/css that is used in FF UI.