Index: wp-content/themes/twentyten/editor-style.css
===================================================================
--- wp-content/themes/twentyten/editor-style.css	(revision 53760)
+++ wp-content/themes/twentyten/editor-style.css	(working copy)
@@ -295,3 +295,7 @@
 .wp-smiley {
 	margin: 0;
 }
+
+.wp-block-buttons > .wp-block {
+	height: auto;
+}