Menu Height

Hi there,
I’m new here in the forum but I’ve been running my website for like almost one year and a half or something. The most problems I could solve myself but I thing the problem I have know is to difficult.
As you can see on my website (www.springhunters.com) my menu is under the header slider and as you can see as well its height it is way too much for the letter size and half of it would be enough. After I changed some text widgets on the main sidebar (I basically just edited the Facebook widget and added the twitter widget) suddenly the menu bar was double of its normal size. I don’t find any line in style.css that says something about the menu “height” and any forum topic could not help me either.
It would be awesome if you can help me out here,
thanks max