How to influence option selected by css

Want option selected in an other background color

[jetteroheller]

I just do not find out how to influence only option selected

[Setek]

Keeping in mind this will only work when the attribute

selected

is used in the x/html, and will only work for those browsers that support attribute selectors:

option[selected] { background: #f00; }

If you want on-the-fly selected, as a user selects it, I would have to vote javascript, because I don't think there's a solution that actually encompasses IE 6.