diff --git a/src/util/CSSClassNames.h b/src/util/CSSClassNames.h
index 05a5524..dba8ce4 100644
--- a/src/util/CSSClassNames.h
+++ b/src/util/CSSClassNames.h
@@ -7,6 +7,11 @@
 #ifndef CSSCLASSNAMES_H__
 #define CSSCLASSNAMES_H__
 
+
+/*
+ * should be consistent with base.css and pdf2htmlEX.js
+ */
+
 namespace pdf2htmlEX {
 namespace CSS {