how can I apply a CSS stylesheet to all page views in my Firefox browser
I would like to apply a CSS stylesheet to all page views in a Firefox browser using a menu option and be able to toggle this when required. (The functionality I want exists in IE: Tools | Internet Options | Accessibility | Format Documents Using my Stylesheet (although I think this may affect pages outside of simply IE).
you can use Stylish, you can define global styles in firefox and ability to switch it on and off fast from Firefox.
Global styles, you can see code and how it is done.