function showModal(targetDiv) {
//targetDiv = "quiz";
	pageW = document.body.clientWidth;
	pageH = document.body.clientHeight;
	pageH2 = document.documentElement.clientHeight;
	pageW = document.body.clientWidth;
	pageH = document.body.clientHeight;
	pageH2 = document.documentElement.clientHeight;
	
	if(pageH >= pageH2) {
	document.getElementById('modalLayer').style.width = pageW+"px";
	document.getElementById('modalLayer').style.height = pageH+"px";
	} else {
	document.getElementById('modalLayer').style.width = pageW+"px";
	document.getElementById('modalLayer').style.height = pageH2+"px";
	}


  var scrOfX = 0, scrOfY = 0;
  if( typeof( window.pageYOffset ) == 'number' ) {
    //Netscape compliant
    scrOfY = window.pageYOffset;
    scrOfX = window.pageXOffset;
  } else if( document.body && ( document.body.scrollLeft || document.body.scrollTop ) ) {
    //DOM compliant
    scrOfY = document.body.scrollTop;
    scrOfX = document.body.scrollLeft;
  } else if( document.documentElement && ( document.documentElement.scrollLeft || document.documentElement.scrollTop ) ) {
    //IE6 standards compliant mode
    scrOfY = document.documentElement.scrollTop;
    scrOfX = document.documentElement.scrollLeft;
  }
  var z = scrOfY+160
  var z400 = scrOfY+400
  var zz = (pageW - 400)/2
  document.getElementById(targetDiv).style.top = z + "px";
  document.getElementById(targetDiv).style.left = zz + "px"; 
	document.getElementById('modalLayer').style.visibility = "visible";
	document.getElementById(targetDiv).style.visibility = "visible";	
}
	
function hideModal(targetDiv) {
	document.getElementById('modalLayer').style.visibility = "hidden";
	document.getElementById(targetDiv).style.visibility = "hidden";
}