I've occasionally used Stylish to improve usability of websites on the PC. Is there an equivalent for Android - either plugin to FireFox, the default browser (mine is a Galaxy Note), or other. Basically, there are some sites that don't have mobile-specific stylesheets that I'd love to improve with a bit of CSS...
According to Mobyware there's a Stylish-Custom Addon available for the mobile Firefox. The page also mentions you need the Stylish Addon itself to make it work -- however, I could not find that. The compatibility list starts with Android 2.0 and goes up through the version to 4.0 (ICS), a list of compatible devices is available as well.
Moreover, some discussions on userstyles.org seem to mention some availability for Android, you might want to check them out.
Not sure if it works, I didn't try myself as I do not use the mobile Firefox -- but you might give it a try.