var amenuitem = new Image();
var imenuitem = new Image();
amenuitem.src = "img/elements/amenuitem.gif";
imenuitem.src = "img/elements/imenuitem.gif";

function switch_sub(subnavi)
{
  var elem = document.getElementById(subnavi);



  if (elem.style.display == "block")
    elem.style.display = "none";
  else
    elem.style.display = "block";
}