Menu in Twenty ten acting strange.

Hi!
I’ve been editing some stuff in style.css, and suddenly the menu is acting strange. Take a look at duta.dambergs.dk
For one, the child menu is shifted a bit to the right, so it’s not directly under the static parent menu button. Secondly, the child menu disappears when you drag the mouse down to it, but sometimes it doesn’t.
I feel like the mistake should be found somewhere here:

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Please help!