function setClasses (obj) {
	var childs = obj.children;
	if (childs.length == 1) childs[0].addClassName('single');
 	childs[0].addClassName('first');
 	childs[childs.length - 1].addClassName('last');
}


window.onload = function () {
	$$('.ebene2').each(setClasses);
	$$('.ebene3').each(setClasses);
	$$('.ebene4').each(setClasses);
};