Border around the Website-Logo

At first: Sorry for my bad english. I'm not a native speaker... ;)

Now we come to my problem: Since yesterday there's a border around my Logo. You can see it here: http://www.das-fanmagazin.de/hannover96/

Therefore I wrote "a img {border: 0px;}" at the end of the CSS-file, but this didn't help. You can see the CSS-File here: http://www.das-fanmagazin.de/hannover96/themes/pixture/style.css

Have you got an idea to fix this problem? I'm helpless... :-(

Thanks a lot ahead!