Most important Web Style Rule

It was very hard for me to come up with one rule that was more important that any other. After looking over websites that others in the class created I realized there was one web style rule that should always be followed: Don't use black or dark backgrounds and light text.

Lynch and Horton's Web Style Guide says, "Subtle pastel shades of colors typically found in nature make the best choices for background or minor elements. Avoid bold, highly saturated primary colors except in regions of maximum emphasis, and even there use them cautiously." I agree that pastel colors with a Dark text are best. Pastels are pleasant to look at on a webpage because they are soft colors. Bright colors hurt to look at them on the computer for too long.
In Spiderpro's 100 do's and dont's of web design they say, "Dark backgrounds tend to make text less readable. So avoid darkcolors or dark backgroundimages. If you do need them, use a
nonserif font for the text (like Arial, Universe, Helvetica) and be sure to not to use a small fontsize."

There are times when a dark background is appropriate. If designed without too much text and the right fonts dark backgrounds can look nice. However, I feel that for the average web designer dark backgrounds should be avoided at all costs.