<link href="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3.2/css/bootstrap-combined.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//netdna.bootstrapcdn.com/twitter-bootstrap/2.3.2/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<div class="container">
<div class="row">
<div class="well" style="width:300px; padding: 8px 0;">
<div style="overflow-y: scroll; overflow-x: hidden; height: 500px;">
<ul class="nav nav-list">
<li><label class="tree-toggler nav-header">Header 1</label>
<ul class="nav nav-list tree">
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
<li><label class="tree-toggler nav-header">Header 1.1</label>
<ul class="nav nav-list tree">
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
<li><label class="tree-toggler nav-header">Header 1.1.1</label>
<ul class="nav nav-list tree">
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li class="divider"></li>
<li><label class="tree-toggler nav-header">Header 2</label>
<ul class="nav nav-list tree">
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>
<li><label class="tree-toggler nav-header">Header 2.1</label>
<ul class="nav nav-list tree">
<li><a href="#">Link</a></li>
<li><a href="#">Link</a></li>