<!--
// showlayer functions done with brute force
// (could use an array of these things to simplify 
// the code).

function showlayer1() {
  document.getElementById("layer1").style.display="block";
  document.getElementById("layer2").style.display="none";
  document.getElementById("layer3").style.display="none";
  document.getElementById("layer4").style.display="none";
}

function showlayer2() {
  document.getElementById("layer1").style.display="none";
  document.getElementById("layer2").style.display="block";
  document.getElementById("layer3").style.display="none";
  document.getElementById("layer4").style.display="none";
}


function showlayer3() {
  document.getElementById("layer1").style.display="none";
  document.getElementById("layer2").style.display="none";
  document.getElementById("layer3").style.display="block";
  document.getElementById("layer4").style.display="none";
}


function showlayer4() {
  document.getElementById("layer1").style.display="none";
  document.getElementById("layer2").style.display="none";
  document.getElementById("layer3").style.display="none";
  document.getElementById("layer4").style.display="block";
}
	
	
//-->