I disagree. Browser side user-css files are the solution to this 'problem' (honestly, my main gripe is low contrast, mainly the gray on white that is the last fashion these days)

opera is the only one that got it right. easy to write the css in a way it works for most sites, and a very convenient way to turn it on/off. too bad opera is ridden with bugs since 8.5 and so i gave up.