Theme – Forums doesnt look fine but topic yes

Hello,

Here is my problem :

The path
http://concours-bonsplans.be/forums/ don’t show good, I always see my sidebar and the visual aspect is not good but when I go on a topic, example : http://concours-bonsplans.be/forums/forum/bons-plans/ the look and feel is now good.

How can I make the http://concours-bonsplans.be/forums working good like the topic and without the sidebar.

Regarding the sidebar I only modify my css template file (display none for sidebar 1).

Hope that someone have an idea.

Regards,

Antoine