Sidebar on the Left – Twenty Twelve

A quick fix to move the sidebar location in a child theme of Twenty Twelve;

add these styles to style.css of the child theme:

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

/*-- move sidebar to the left --*/
@media screen and (min-width: 600px) {
	.site-content {
		float: right;
	}
	.widget-area {
		float: left;
	}
}

/* for IE8 and IE7 ----------------*/
.ie .site-content {
	float: right;
}
.ie .widget-area {
	float: left;
}

caveat: this simplified set of styles has some problems with the formatting of the widgets in the ‘front-page’ template, when viewed in older browsers such as IE7.

possible helpful styles:

.ie .template-front-page #secondary.widget-area { width: 100%; }
.ie .template-front-page #secondary.widget-area .first.front-widgets { width: 50.1%; margin-right: 3%; background: #f4f4f4; }
.ie .template-front-page #secondary.widget-area .second.front-widgets { width: 46.8%; margin-right: 0; background: #f4f4f4; }
.ie .template-front-page #secondary.widget-area .widget { width: 100%; }