<link id="dyncss" rel="stylesheet" type="text/css" href="">   
<script type="text/javascript">   
function setDynCSS(url) {   
if (!arguments.length) {   
url = (url = document.cookie.match(/\bdyncss=([^;]*)/)) && url[1];   
if (!url) return '';   
}   
document.getElementById('dyncss').href = url;   
var d = new Date();   
d.setFullYear(d.getFullYear() + 1);   
document.cookie = ['dyncss=', url, ';expires=', d.toGMTString(), ';path=/;'].join('');   
return url;   
}   
setDynCSS();   
</script>

<img style="cursor:pointer;" src="http://novofilms.ru/design/rega/2.png" onclick="setDynCSS('1.css')">   
<img style="cursor:pointer;" src="http://novofilms.ru/design/rega/1.png" onclick="setDynCSS('2.css')">