Index: wp-content/themes/twentytwelve/style.css
===================================================================
--- wp-content/themes/twentytwelve/style.css	(revision 21664)
+++ wp-content/themes/twentytwelve/style.css	(working copy)
@@ -1302,7 +1302,7 @@
 @media screen and (min-width: 600px) {
 	.entry-content p,
 	.entry-summary p {
-		text-align: left;
+		text-align: inherit;
 		text-justify: auto;
 	}
 	#author-avatar {