Provide CSS for input boxes

[wtl420]

I have this issue on a lot of websites, where the site doesn't provide CSS for input boxes and the like, so it'll default to my system theme. (A more annoying case, which isn't the case here, is where input boxes have text color defined but not background, so it ends up being dark text on that dark grey background).

It'd be best to not make assumptions about input boxes and have them have set colors to match whatever theme the board is styled for.