I messaged Ron and Calypso about the missing forum banner and they both suggested to ask eviltrout which I did too. He found the problem and added the banner again. I thought it looks a little odd compared to how it looked before it was gone, maybe just because of the positioning or cutout he used.
So I searched online to find a complete pic of the banner to see how a diffenrent cutout would look.
Instead I found a game analysis
someone somebody wrote at the university in bayreuth Germany.
So whoever is interessted and can read german text, here it is:
PS: I found the banner on my own harddrive