I'm frequently reminded that the most readable and accessible (albeit, admittedly, boring) websites out there are ones that are just plain old-school HTML–no javascript, no CSS, or anything like that.
I doubt it.
CSS can be a whole lot less than just fancy floats and parallax scrolling.
I do realise I'm basically describing Gopher here, and there's possibly a reason it didn't take off...
If only browsers provided better defaults. As it stands, very few people would consider the browser defaults acceptable.
> it's no surprise Wikipedia uses black text on a white background with blue hyperlinks
Yes, Wikipedia does use black text, a white background, and blue links. But they do not merely rely upon the default browser stylesheets. They use custom font-face, font-size, line-height, and margin properties even for the basic <p> tag. And that's saying nothing about all the other elements that often have borders, padding, backgrounds, and so on.
There's a lot to be said about the Svbtle/Medium-style design with a small column running down the center of the page.
The full-width text does get a bit annoying when you're trying to read Wikipedia on a 30" screen, but in that case, nothing's preventing you from snapping the browser window to the left or right half of the screen and/or increasing the zoom level to make for more comfortable reading.
#content { width: 100%; max-width: 600px; margin: 0 auto; }