by Nobbie » 04. April 2015 08:32
Because you installed it with ServerName (Domain or Hostname) like "localhost", but your friends do not use "localhost", they use an IP or similar and all linked pictures and styesheets that yield to localhost cannot be found, because localhost is THEIR OWN PC and not your server. You must apply the public IP of your site during installation, if you want to access it from external PCs later on.