That is because your server is blocking access to files that are not from http://www.yesindeed.de. You can see these types of errors by looking into the browser console. In chrome browser you can view that navigating to View > Developer > Javascript Console.
Below is one of the errors yesindeed.de your homepage when accessing yesindeed.de:
Access to Font at 'http://www.yesindeed.de/wp-content/themes/click-mag-child/font-awesome/fonts/fontawesome-webfont.woff2?v=4.6.3' from origin 'http://yesindeed.de' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://yesindeed.de' is therefore not allowed access.
The best fix for this would be to redirect all traffic for yesindeed.de to http://www.yesindeed.de via htaccess. Try using the code below:
RewriteEngine On
RewriteCond %{HTTP_HOST} ^yesindeed.de [NC]
RewriteRule ^(.*)$ http://www.yesindeed.de/$1 [L,R=301]
Hope this helps!
You just made my day!
Thanks a lot, junixblog! =)