Please note, I'm an Editor not a website programmer but one problem we had was that we'd get periodic e-mails saying, "Why do you use black text on dark blue for your stories, it's hard to read?"
However, we didn't use that combination, we used white text on mid-dark'ish blue, via style sheets for all fonts. The problem was obviously when the style sheets hadn't loaded that they were getting problems.
Now, I have seen our site (and others) appear *on occasion* without the style sheets, very rare though. Also, when you refresh or click to go the next page, they load and all is fine. So, I wonder why those people who complained didn't just see the 'wrong look' once and then see the site the correct way on the next page? Are there some browsers that can't interpret CSS (like viewing from a Dreamcast on TV etc.)
Anyway, the w/master set the default text colour (i.e. if CSS didn't load) to white or whatever and ever since then, no-one has e-mailed.
Not sure if this makes sense to you, but hope it helps?!