It alarms me that so many sites have no background color. That’s right, NO background color. Sure, they look fine, but only by accident: I changed my browser’s default colors to blue text on a yellow background, and I’m seeing a lot of yellow these days (and a little bit of blue). Not everywhere, but enough places to know that a lot of sites are RELYING on your browsers default settings being unchanged. A quick look into the code confirms this.

Come on, site owners! All it takes is a body { background: white; } and you are in the clear, as they say.