CSS Style being overridden by post CSS?

Just upgraded Blogs MU from 1.3.1 to 1.3.4. Now my sidebar is too wide (or the content area) and the sidebar appears at the bottom of the page. I’m using the child theme but I didn’t see anything I needed to upgrade there. Yes, I’ve got some custom styling in my child-style.css file. Changing settings there don’t seem to do anything.

This seems to happen everytime I upgrade. So let’s start simple and let me know what I need to do with any new files or the child theme files after an upgrade like this.