Ouch. Good thing I’m sitting down. Just came from a website that has excellent content but they had white text on black background. Oh! My eyes are so crossed now I have trouble focusing. When I studied advertising in college, one of the key things they teach you is – don’t put your copy on a dark background. White on black is the worst. It’s bad enough on printed material, it’s harder on the eyes in electronic format.
White on black is OK if you have a large, attention grabbing headline or something that has a lot of design in it but not good for text. Absolute not for an article with hundreds of words on it, no matter how good the content/copy. If you want to have a dark background at least set the content area to white or a very light color.