Split into more lists??
Code:
<body>
<h2>Index</h2>
<ul id="miniflex">
<li><a href="../Text/colophon.xhtml" title="">Colophon</a></li>
<li><a href="../Text/colophon.xhtml" onclick="if(document.getElementById('spoiler') .style.display=='none') {document.getElementById('spoiler') .style.display=''}else{document.getElementById('spoiler') .style.display='none'}" title="spoiler">Capitoli</a></li>
</ul>
<div id="spoiler" style="display:none">
<ul id="miniflex2">
<li><a href="../Text/Capitolo1.xhtml" title="">Capitolo 1</a></li>
<li><a href="../Text/Capitolo2.xhtml" title="">Capitolo 2</a></li>
<li><a href="../Text/Capitolo3.xhtml" title="">Capitolo 3</a></li>
<li><a href="../Text/Capitolo4.xhtml" title="">Capitolo 4</a></li>
<li><a href="../Text/Capitolo5.xhtml" title="">Capitolo 5</a></li>
...
...
...
</ul>
</div>
<ul id="miniflex3">
<li><a href="../Text/playlist.xhtml" title="">Archivio Audio</a></li>
</ul>
</body>
</html>