Non l'ho provato. In rosso le aggiunte. Fammi sapere... P.S. Credo che affinché funzioni debba trovarsi online!

codice:
<!doctype html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Pagina vuota</title>
<link href="static.css" rel="stylesheet" type="text/css" />
<link href="default.css" rel="stylesheet" type="text/css" title="Default Style" />
<link href="fancy.css" rel="stylesheet" disabled="true" type="text/css" title="Fancy" />
<link href="basic.css" rel="stylesheet" disabled="true" type="text/css" title="Basic" />
<script type="text/javascript">
function chooseStyleSheet(sTitle) {
	if (!sTitle) { return; }
	for (var iStyleSh, iStyleSheetId = 0, aLinkEls = document.getElementsByTagName("link"); iStyleSheetId < aLinkEls.length; iStyleSheetId++) {
		iStyleSh = aLinkEls[iStyleSheetId];
		if (iStyleSh.rel === "stylesheet" && iStyleSh.title) { iStyleSh.disabled = iStyleSh.title !== sTitle; }
	}
	localStorage.setItem("customStyle", sTitle);
}
</script>
</head>

<body onload="if(localStorage.hasOwnProperty('customStyle')){chooseStyleSheet(localStorage.getItem('customStyle'));}">


[ <span class="intLink" onclick="chooseStyleSheet('Default Style');">Default Style</span> | <span class="intLink" onclick="chooseStyleSheet('Fancy');">Fancy</span> | <span class="intLink" onclick="chooseStyleSheet('Basic');">Basic</span> ]</p>


<span class="classeEsempio">Testo di esempio</span>



</body>
</html>