chrome-problem: more-link-anchor shifts header

Hi everybody,
I have a strange problem with my page. if a visitor has used the more-link, the header moves partly in an invisible area. The problem occures when the page automatically jumps down to an anchor. If the visitor then scrolls up the navigation has moved … :S

I disabled all my page elements one by one. The problem is solved if I replace “the_content” by “the_excerpt” or remove “the_content” entirely. ! I don’t have any idea why this happens.

The problem occurs only in Chrome. I am using version 11

Example: You can see this error here: https://kulturbanause.de/2011/04/facebook-so-nutzt-ihr-den-neuen-send-button/#more-4869

Does anybody have a hint for me?

thanks in advance!