Index: wp-content/themes/twentytwelve/functions.php
===================================================================
--- wp-content/themes/twentytwelve/functions.php	(revision 23713)
+++ wp-content/themes/twentytwelve/functions.php	(working copy)
@@ -318,10 +318,10 @@
 			<header class="comment-meta comment-author vcard">
 				<?php
 					echo get_avatar( $comment, 44 );
-					printf( '<cite class="fn">%1$s %2$s</cite>',
+					printf( '<cite><b class="fn">%1$s</b> %2$s</cite>',
 						get_comment_author_link(),
 						// If current post author is also comment author, make it known visually.
-						( $comment->user_id === $post->post_author ) ? '<span> ' . __( 'Post author', 'twentytwelve' ) . '</span>' : ''
+						( $comment->user_id === $post->post_author ) ? '<span>' . __( 'Post author', 'twentytwelve' ) . '</span>' : ''
 					);
 					printf( '<a href="%1$s"><time datetime="%2$s">%3$s</time></a>',
 						esc_url( get_comment_link( $comment->comment_ID ) ),