toggleWerkgebied = function(el) {
 if(el.className.match("werkgebied_active")) {
   el.className = el.className.replace(/ werkgebied_active/g,'');
 }
 else {
   el.className = el.className + ' werkgebied_active';
 }
 for (i=0; i<el.childNodes.length; i++) {
  node = el.childNodes[i];
  if(node.className == "vacatures") {
    new Effect.toggle(node,'blind',{ duration: 0.5 });
  }
 }
 return false;
}