Index: wp-content/themes/twentytwelve/style.css
===================================================================
--- wp-content/themes/twentytwelve/style.css	(revision 21437)
+++ wp-content/themes/twentytwelve/style.css	(working copy)
@@ -258,6 +258,11 @@
 	box-shadow: none;
 	padding: 0;
 }
+input#searchsubmit,
+article.post-password-required input[type=submit] {
+	padding: 6px 10px;
+	padding: 0.4rem 0.714285714rem;
+}
 
 /* Form fields */
 .widget_search input[type="text"],