After freak wordpress mess, can't get column to center….

I was fixing a couple things on my wife’s blog (blog.michelleheaps.com) and a bunch of stuff went wrong. It kept me from logging in by showing the “white screen of death”, modified a few things, finally got in, but now the pages are not centered anymore. I can’t figure out how to change it back and was hoping someone might be able to point me in the right direction. Thanks.