Index: wp-content/themes/twentythirteen/comments.php
===================================================================
--- wp-content/themes/twentythirteen/comments.php	(revision 23686)
+++ wp-content/themes/twentythirteen/comments.php	(working copy)
@@ -50,6 +50,6 @@
 
 	<?php endif; // have_comments() ?>
 
-	<?php comment_form(); ?>
+	<?php comment_form( array( 'format' => 'html5' ) ); ?>
 
 </div><!-- #comments -->
\ No newline at end of file
Index: wp-content/themes/twentythirteen/style.css
===================================================================
--- wp-content/themes/twentythirteen/style.css	(revision 23686)
+++ wp-content/themes/twentythirteen/style.css	(working copy)
@@ -2406,7 +2406,9 @@
 	color: #ed331c;
 }
 
-#commentform input[type="text"] {
+#commentform input[type="text"],
+#commentform input[type="email"],
+#commentform input[type="url"] {
 	max-width: 270px;
 	width: 60%;
 }
@@ -3027,7 +3029,9 @@
 		width:         calc(100% - 104px);
 	}
 
-	#commentform input[type="text"] {
+	#commentform input[type="text"],
+	#commentform input[type="email"],
+	#commentform input[type="url"] {
 		width: -webkit-calc(100% - 100px);
 		width:         calc(100% - 100px);
 	}