diff --git a/demo/variableheight.html b/demo/variableheight.html
index ab241c6d28ae13fcd8dd8d3f1ab2903ba4f21435..98f2fd29d054eb0c6617a54ff3fe05ca2d52f332 100644
--- a/demo/variableheight.html
+++ b/demo/variableheight.html
@@ -11,12 +11,12 @@
 <style type="text/css">
       .CodeMirror {border: 1px solid silver; border-width: 1px 2px; }
       .cm-header { font-family: arial; }
-      .cm-header1 { font-size: 150%; }
-      .cm-header2 { font-size: 130%; }
-      .cm-header3 { font-size: 120%; }
-      .cm-header4 { font-size: 110%; }
-      .cm-header5 { font-size: 100%; }
-      .cm-header6 { font-size: 90%; }
+      .cm-header-1 { font-size: 150%; }
+      .cm-header-2 { font-size: 130%; }
+      .cm-header-3 { font-size: 120%; }
+      .cm-header-4 { font-size: 110%; }
+      .cm-header-5 { font-size: 100%; }
+      .cm-header-6 { font-size: 90%; }
       .cm-strong { font-size: 140%; }
     </style>
 <div id=nav>