Sidebar Width

Hi,

I am using a Twenty Eleven Child Theme. Here’s my site:
http://goo.gl/03sHi

I’d like to change the width of my right sidebar. In the Forum I read that I need to increase the width of the PRIMARY from 70% (what my site has now) to 100%. When I am doing this my sidebar increasing but slides down to the bottom of the page.

Any help appreciated. Thanks!!