Index: wp-content/themes/twentythirteen/style.css
===================================================================
--- wp-content/themes/twentythirteen/style.css	(revision 23585)
+++ wp-content/themes/twentythirteen/style.css	(working copy)
@@ -2472,7 +2472,7 @@
 }
 
 .widget .widget-title {
-	font: 300 italic 20px "Source Sans Pro", Helvetica, sans-serif;
+	font: 300 italic 19px "Source Sans Pro", Helvetica, sans-serif;
 	margin: 0 0 10px;
 }