I try to make the same menu like you did, it work no problem:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml2/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script>
<script type="text/javascript" src="ddaccordion.js">
/***********************************************
* Accordion Content script- (c) Dynamic Drive DHTML code library (www.dynamicdrive.com)
* Visit http://www.dynamicDrive.com for hundreds of DHTML scripts
* This notice must stay intact for legal use
***********************************************/
</script>
<style type="text/css">
.mypets{ /*header of 1st demo*/
cursor: hand;
cursor: pointer;
padding: 2px 5px;
border: 1px solid gray;
background: #E1E1E1;
}
.openpet{ /*class added to contents of 1st demo when they are open*/
background: yellow;
}
}
</style>
<script type="text/javascript">
//Initialize first demo:
ddaccordion.init({
headerclass: "expandable", //Shared CSS class name of headers group
contentclass: "categoryitems", //Shared CSS class name of contents group
revealtype: "click", //Reveal content when user clicks or onmouseover the header? Valid value: "click", "clickgo", or "mouseover"
mouseoverdelay: 200, //if revealtype="mouseover", set delay in milliseconds before header expands onMouseover
collapseprev: true, //Collapse previous content (so only one open at any time)? true/false
defaultexpanded: [0], //index of content(s) open by default [index1, index2, etc]. [] denotes no content.
onemustopen: false, //Specify whether at least one header should be open always (so never all headers closed)
animatedefault: false, //Should contents open by default be animated into view?
persiststate: true, //persist state of opened contents within browser session?
toggleclass: ["", ""], //Two CSS classes to be applied to the header when it's collapsed and expanded, respectively ["class1", "class2"]
togglehtml: ["none", "", ""], //Additional HTML added to the header when it's collapsed and expanded, respectively ["position", "html1", "html2"] (see docs)
animatespeed: "fast", //speed of animation: integer in milliseconds (ie: 200), or keywords "fast", "normal", or "slow"
oninit:function(expandedindices){ //custom code to run when headers have initalized
//do nothing
},
onopenclose:function(header, index, state, isuseractivated){ //custom code to run whenever a header is opened or closed
//do nothing
}
})
</script>
</head>
<body>
<h3 class="menuheader expandable">About me</h3>
<ul class="categoryitems" style="margin-bottom:-12px; padding-top:15px;">
<li><a href="http://www.">CV Download</a></li>
</ul>
<h3 class="menuheader expandable">Projects</h3>
<ul class="categoryitems" style="margin-bottom:-12px; padding-top:15px;">
<li><a href="http://www." >All </a></li>
<li><a href="http://www.">Housing</a></li>
</ul>
<h3 class="menuheader expandable">Stuff i like</h3>
<ul class="categoryitems" style="margin-bottom:-12px; padding-top:15px;">
<li><a href="http://www." >Photo</a></li>
<li><a href="http://www.">Design</a></li>
</ul>
<h3 class="menuheader expandable"><a href="http://bitacoraurbana.com/?page_id=171" >My Blog</a></h3>
</body>
</html>