Accidentally moved my entire blog’s page alignment from center to left

While trying to get some the posts+sidebar to be the same width as our header graphic (which I did successfully) I also somehow made the entire blog (as a unit) align against the left instead of being centered in the browser window, and I’m not quite sure how. I’ve been liberally sprinkling “align: center”s into the stylesheet with no effect and at this point I feel like I’ve run out of things to modify. Ideas would be much appreciated. Theme is a modified version of Ephemeral.