Widening the Post Area

As part of my posts (www.wheretofeed.com) I add three pictures in a horizontal line. this is not longer possible due to the reduced post-area width. I have tried reducing the thumbnail size but this doesn't seem to have helped. Is it possible to increase the width of the post area to solve my problem? I really like the theme but I'm just trying to solve a few niggles with the content I already have.