2012 theme page padding all messed up

When I last looked at this site, the page padding was fine. Now suddenly it’s all gone flush to the left edge, and I haven’t edited anything. Can you tell me how to rectify this?

The site is here:
http://blindwilliejohnson.com

The child theme css contains the following additions, affecting screen width, not padding. I’m confused how this changed.

/*
Theme Name: Twenty Twelve Child
Theme URI: http://www.blindwilliejohnson.com
Author:
Author URI:
Template: twentytwelve
Description: Child theme for Twenty Twelve
Version:
License: GNU General Public License v2 or later
License URI: http://www.gnu.org/licenses/gpl-2.0.html
Tags: light, gray, white, one-column, two-columns, right-sidebar, flexible-width, custom-background, custom-header, custom-menu, editor-style, featured-images, flexible-header, full-width-template, microformats, post-formats, rtl-language-support, sticky-post, theme-options, translation-ready
Text Domain: twentytwelve

This theme, like WordPress, is licensed under the GPL.
Use it to make something cool, have fun, and share what you've learned with others.
*/

@import url("../twentytwelve/style.css");

/* This Block Adjusts the Overall Theme Width */
footer[role="contentinfo"] {
	max-width: 1100px;
}
@media screen and (min-width: 600px) {
	.site {
		max-width: 1100px;
		max-width: 78.571428571rem;
	}
}
.ie .site {
	max-width: 1100px;
}