I changed the layout of my blog from 3 columns to 2 columns using the CSS customizations found in this thread (http://en.forums.wordpress.com/topic/oxygen-theme-how-to-make-full-width-posts?replies=17), but now I can't figure out how to widen the featured images for each post. I would like for the images to extend to the gray box where the category is (if that makes sense) but it is still defaulted to the width it was at in the 3-column layout. What is the CSS customization for this—or is it possible? Thanks!
The blog I need help with is smithsonian20.wordpress.com.