Topic: Viewtopic width - Where to change

I can't get it correctly, so who could give me a hint:

The display of the posts don't show correctly,  the are cuted at the right side. The red area should be used. I'm blind where and which Parameters does I have to change.
http://www.galopp-sport.eu/forumgalopp/postview.gif

thanks for your help

The poor horseman without horses
www.galopp-sport.eu

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