Minor fix for #2396

public/less/_markdown.less

@@ -458,6 +458,10 @@
 		box-shadow:inset 0 -1px 0 #bbb;
 	}
 
+	input[type="checkbox"] {
+		vertical-align: middle !important;
+	}
+
 	.csv-data td,
 	.csv-data th {
 		padding:5px;