[Theme: twenty eleven] How do I adjust the sidebar length?

Hello, I’m trying to adjust the sidebar length of the sidebar on my twenty eleven child theme. I want the sidebar to go to the end of the content on each page. It initially did that on my home page but fell way too short on others (particularly the page titled “The Professional.”) I tried to fix that but now the sidebar is ridiculously long on every page and they all scroll forever.

Here’s my site: http://stephenrstone.com

Here is the code for the sidebar. At least I think it is. It’s what I edited to cause the sidebar to go all screwy and now it won’t go back to normal, even if I revert the code to where it was.

#secondary {
float: right;
margin-right: 0.21%;
width: 21%;
height: 100%;
background:#333;

}

Any help would be greatly appreciated.

Thanks.