I've been trying a ff plugin called Stylish, which overrides css in websites. The only problem is there is no way to toggle back to standard view. Because i work as a web designer/developer i need an extension for either chrome or ff that can do this and then i'll use that for my primary 'browsing' browser

any tips would be greatly appreciated!

ps. I've also tried changing colors in firefox>>settings>>content>>colors but again there is no quick toggle