With missing header resulted html output has different structure that
break CSS for TOC and title.
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>tips index</title>
</head>
<frameset cols="220,*">
<frame src="frame-index.html" name="toc">
<frame src="README.html" name="article">
</frameset>
</html>