function navAn()
 {
  document.getElementById("nav2").style.display="block";
  document.getElementById("nav3").style.display="block";
  document.getElementById("nav4").style.display="block";
  document.getElementById("nav5").style.display="block";
  document.getElementById("nav6").style.display="block";
  document.getElementById("nav7").style.display="block";
 }

 function navAus()
 {
  document.getElementById("nav2").style.display="none";
  document.getElementById("nav3").style.display="none";
  document.getElementById("nav4").style.display="none";
  document.getElementById("nav5").style.display="none";
  document.getElementById("nav6").style.display="none";
  document.getElementById("nav7").style.display="none";
 }