Untitled

===
AAA
===

aaa

BBB
===

bbb

SUB
---

sub

CCC
===

ccc


SUBC
----

nnnn


produces:
<body>
<div class="document" id="aaa">
<h1 class="title">AAA</h1>
<p>aaa</p>
<div class="section">
<h1><a id="bbb" name="bbb">BBB</a></h1>
<p>bbb</p>
<div class="section">
<h2><a id="sub" name="sub">SUB</a></h2>
<p>sub</p>
</div>
</div>
<div class="section">
<h1><a id="ccc" name="ccc">CCC</a></h1>
<p>ccc</p>
<div class="section">
<h2><a id="subc" name="subc">SUBC</a></h2>
<p>nnnn</p>
</div>
</div>
</div>
</body>
</html>