Q&A plugin wrecks havoc on my theme

Hi, I've installed Q&A and on the questions/ask page the styling has gone all whack.

http://184.172.185.14/~xpand201/questions/ask/

I've added some css to get the wrappers background white:

#qa-page-wrapper {
background: none repeat scroll 0 0 #FFFFFF;
float: left;
padding: 120px 0 0;
}

But as you can see it has made the rest of the page grey in background which is very weird.

Thanks for your help.

Ellissa