// von http://forum.jswelt.de/javascript/32597-externe-css-datei-per-js-modifizieren.html
///////////////////////////////////////////////////////////
// setStyle(name, attr, value)
function setStyle(name, attr, value)
{
    var rule = name;
    if(!rule) return alert("kein Stylesheet");
    if(typeof value != 'undefined') rule.style[attr] = value;
    alert(attr+'='+rule.style[attr]);
    return rule.style[attr];
}
///////////////////////////////////////////////////////////
// getStyleSheet(name)
function getStyleSheet(name)
{
     if(!name || !document.styleSheets) return null;

     var i = document.styleSheets.length;
     while(i--)
     {
         var rules = (typeof document.styleSheets[i].rules != 'undefined') ?
         document.styleSheets[i].rules : // IE
         document.styleSheets[i].cssRules; // MZ
         var j = rules.length;
         while(j--)
         {
             if(rules[j].selectorText == name) return rules[j];
         }
     }
     return null;
}