Index: src/wp-admin/css/customize-controls.css
===================================================================
--- src/wp-admin/css/customize-controls.css	(revision 31459)
+++ src/wp-admin/css/customize-controls.css	(working copy)
@@ -452,6 +452,10 @@
 	cursor: pointer;
 }
 
+.customize-control-hidden {
+	margin-bottom: 0;
+}
+
 #customize-preview iframe {
 	width: 100%;
 	height: 100%;