function change1a() {
 if(document.getElementById("bgr1").className == "nvis1")
  document.getElementById("bgr1").className = "on1";
}

function change1b() {
 if(document.getElementById("bgr1").className == "on1")
  document.getElementById("bgr1").className = "nvis1";
}

function change2a() {
 if(document.getElementById("bgr2").className == "nvis2")
  document.getElementById("bgr2").className = "on2";
}

function change2b() {
 if(document.getElementById("bgr2").className == "on2")
  document.getElementById("bgr2").className = "nvis2";
}

function change3a() {
 if(document.getElementById("bgr3").className == "nvis3")
  document.getElementById("bgr3").className = "on3";
}

function change3b() {
 if(document.getElementById("bgr3").className == "on3")
  document.getElementById("bgr3").className = "nvis3";
}

function change4a() {
 if(document.getElementById("bgr4").className == "nvis4")
  document.getElementById("bgr4").className = "on4";
}

function change4b() {
 if(document.getElementById("bgr4").className == "on4")
  document.getElementById("bgr4").className = "nvis4";
}

function Bildwechsel(Bildnr,Bildobjekt) {
  window.document.images[Bildnr].src = Bildobjekt.src;
}

  Normal1 = new Image();
  Normal1.src = "projekt1.gif";
  Highlight1 = new Image();
  Highlight1.src = "projekt2.gif";

  Normal2 = new Image();
  Normal2.src = "texte1.gif";
  Highlight2 = new Image();
  Highlight2.src = "texte2.gif";

  Normal3 = new Image();
  Normal3.src = "filme1.gif";
  Highlight3 = new Image();
  Highlight3.src = "filme2.gif";

  Normal4 = new Image();
  Normal4.src = "kontakt1.gif";
  Highlight4 = new Image();
  Highlight4.src = "kontakt2.gif";