Novice at CSS.

Looking to have the behavior of a combo box be such that when it is in focus, it is displayed in black text and white background (I already know how to do this).

What I don't know how to do is when the combo box becomes expanded, as the user scrolls down the list, the highlighted row is also in reverse video (i.e. black text and white background). The non-selected rows should appear in normal text mode....