comments start under the sidebar

hi there, tis is my first post, i’m fiddling for two weeks with wordpress now and have to say its really fine, but there’s one thing i can’t resolve:

i use the rin theme (http://www.brokenkode.com/rin) on a sports group page which i want to have online by now …

by theme default, the sidebar was meant to disappear when viewing a single post, so i pasted the get_sidebar-code into the single.php …

so far so good … when my friends started commenting, the comments begin at the point where the sidebar ends, which leaves a gap between the post and the comment, look here (http://arthuro.zirona.de/allgemein/ihr-lieben-stammtischler)

i really want to get behind this .. so i if anyone can give me a hint, whether its a css or php problem, i can figure it out myself…

thanks in advance

arthur