function hover(obj){
 obj.firstChild.style.color = "#000000";
 obj.style.backgroundColor = "#ffffff";
 obj.style.backgroundImage = "none";
}

function normal(obj){
 obj.firstChild.style.color = "#ffffff";
 obj.style.backgroundColor = "none";
 obj.style.backgroundImage = "url(images/menubackground.gif)";
}

function aktivieren(id){
 for(var i = 1; i <= 6; i++){
  document.getElementById("navi" +i).className = "navi";
  }
 document.getElementById("navi" +id).className = "naviaktiv";
 document.getElementById("navi" +id).firstChild.style.color = "#000000";
}