I've grown very accustomed to the Chrome developer tools, and I've recently decided to try out Firefox. Best I can tell, you cannot add custom rules in the Firefox inspector tab. For instance, if I inspect the element on an image in Firefox, I am given all the defined styles (rules) for that element. I can, of course, edit those defined styles. However, it does not give me an option to add my own custom styles unless I jump over to the 'Style Editor' tab and write them in manually. This becomes a problem when I want to write in a quick :hover or a :first-child or reference any other selecter that's not already defined. In Chrome, not only do I add/remove/change styles directly in the Inspector, but it also saves a custom inspector stylesheet for me with all the changes I made. Chrome example: http://cl.ly/Wm56 Firefox example: http://cl.ly/WmUP Is there any way to add custom styles directly from the inspector tab in Firefox? Thanks!