No site style when not logged in

Hi dear community,

I got a strange bug. When I’m logged in to the site it’s looks fine as it should and got the needed styles. But when your watching the site without being logged in, you got no css styles.

The site is: xetorian.de

I’ve also included a screenshots:
Site when logged in
Site when logged out

I already checked the permissions and files and there are no errors.

Hope I can get some help here 🙂

Thanks a bunch
Lagger Gandalf