wider content-area and narrower right-sidebar

Hi there, I've been using Adventurous pro theme. What I would like to do is make content-area wider and right-sidebar narrower correspondingly, e.g. 10% wider and 10% narrower. Could you tell me the custom css to make my goal attain? My website is here, http://kenta-kiyomiya.com I know there are similar questions already in support forum, but I couldn't did it alone. Thank you for such a nice wordpress theme and your support. Kenta