Logo Section Problem

I need help with CSS, regarding the logo of my website. The problem is, that it is a bit big, so it streches the section above the content and the navigation-bar. But i want that particular section shallower. The Logo should overlap the navigation-bar.

This is how it currently looks like:
http://i.imgur.com/F77ogDp.png

But it should look like this all the time:
http://i.imgur.com/1J6URil.png

(ignore that these screenshots are censored. That was for another purpose before)

See? There is this bit between the navigation-bar and the logo. I want that gone, but just can’t figure out how.
Can someone help me?

The site is: http://www.fenster-service-ratzmann.de/