fixed overlapping footer, but now single posts are broken

Hi,

I followed the instructions in this helpful thread to fix the overlapping footer issue in twentythirteen: http://wordpress.org/support/topic/sidebar-overlaps-footer-in-twentythirteen

I made some modifications to the code in order to move the sidebar to the left and keep the content on the right as follows:

@media (min-width: 999px) {
	#main {
		overflow: hidden; /* needed to stretch parent container since children are floated */
	}
		#primary.content-area {
		width: 73%;
		float: right;
	}
	.site-main .sidebar-container {
		position: static;
		float: left;
		width: 27%;
		height: auto;
	}
	.sidebar .entry-header, .sidebar .entry-content, .sidebar .entry-summary, .sidebar .entry-meta {
		padding: 0 20px 0 0px;
	}

	.site-main .widget-area {
	padding: 27px 20px 20px 30px;
	}

}

I now have a new problem, however: posts that don’t include a sidebar are now indented to the right instead of being centered. Any suggestions as to how to fix this?

Any help would be much appreciated.

Cheers!