function setHeight(){
			

			a = document.documentElement.clientHeight
			b = document.documentElement.clientWidth
			
			var hc = a - 180
			
			// (166 = header + menu + bottom 101 + 25 + 40)
			//			alert(a + "x" + b + "->" + hc)
				
			main.style.height = hc+"px";

		}

		function showHide(h,s){
			document.getElementById(h).style.display = 'none'
			document.getElementById(s).style.display = 'block'
		}

		function terug(h,s){
			document.getElementById(h).style.display = 'none'
			document.getElementById(s).style.display = 'block'
		}