var layers = new Array("leer","startseite","itservice","internet","kommunikation","philosophie","projekte","beratung","kontakt","referenzen","impressum","startseite2","itservice2","internet2","kommunikation2","philosophie2","projekte2","beratung2","kontakt2","referenzen2","impressum2");
function showHideLayer(id)
  {
  if (document.getElementById)
    {
    var i,layer;
    for (i=0; i<layers.length; i++)
      {
      if ((layer = document.getElementById(layers[i])) != null)
        layer.style.visibility = "hidden";
      }
    if (id)
      document.getElementById(id).style.visibility = "visible";
    }
  }