Styling current menu twentyten

I’m trying to style my default twentyten menu. The mainmenu has different backgrounds for hover and current. When I am on a page and the menu-item has his current background, it works perfect. But when I hover that same current item, so the submenu pops out, the current background has to be changed to the hover background. Otherwise the colours of mainmenu and submenu don’t match. When I add in my css for the hover-image a !important, it works. But than I have also the hover background in the submenu, which I don’t want.
See https://bit.ly/KkrOIe for my test-site.

How can I get this done right?