theme size

I widened out the theme to 980px from 960px, and widened the sidebar, so that I could fit 250px wide ads in the my sidebar. I’m happy with how it looks, however, this has thrown off my mobile page. Now it loads it as one big page with a bunch of space in between the body and the sidebar. Should I have done this differently? Here is the added code:

#container{
	width: 980px;
	margin: 0 auto;
}
#sidebar {
	width: 300px;
	float: right;
	margin-left:20px;
}
#sidebar .widget{
	padding-bottom: 20px;
	margin-bottom:20px;
	width:300px;
	overflow:hidden;
}

my site is hisbigd.com

Thank you!