Как юзеру менять дизайн?

<script type="text/javascript">
function getCookie(name) {
  var matches = document.cookie.match(new RegExp(
    "(?:^|; )" + name.replace(/([\.$?*|{}\(\)\[\]\\\/\+^])/g, '\\$1') + "=([^;]*)"
  ));
  return matches ? decodeURIComponent(matches[1]) : undefined;
}

function setCookie(name, value, options) {
  options = options || {};

  var expires = options.expires;

  if (typeof expires == "number" && expires) {
    var d = new Date();
    d.setTime(d.getTime() + expires*1000);
    expires = options.expires = d;
  }
  if (expires && expires.toUTCString) { 
  	options.expires = expires.toUTCString();
  }

  value = encodeURIComponent(value);

  var updatedCookie = name + "=" + value;

  for(var propName in options) {
    updatedCookie += "; " + propName;
    var propValue = options[propName];    
    if (propValue !== true) { 
      updatedCookie += "=" + propValue;
     }
  }
}

function reset_style(form_id)
{
    var css_file = document.getElementById(form_id).value;
    document.getElementById('link_style').href = css_file;
    setCookie('css_file', css_file, 86400);
}
window.onload=function(){
    document.getElementById('link_style').href = getCookie('css_file');
}
</script>

<link rel="stylesheet" id="link_style" href="style/default.css" type="text/css" />

<form>
<select onchange="reset_style('reset')" id="reset">
                <option value="styles/style1.css">Дизайн 1</option>
                <option value="styles/style2.css">Дизайн 2</option>
                <option value="styles/style3.css">Дизайн 3</option>
            </select>
</form>