var Timer;
var Pas = 3;
function moveLayer(Sens) {
	Objet=document.getElementById("contenu");
	if(parseInt(Objet.style.top) + (Pas*Sens)>0)
		clearTimeout(Timer);
	else
	{
		if(parseInt(Objet.style.top) + (Pas*Sens)<-(Objet.offsetHeight-document.getElementById("description").offsetHeight))
			clearTimeout(Timer);
		else
			Objet.style.top = (parseInt(Objet.style.top) + (Pas*Sens)) + "px";
	}
	Timer = setTimeout("moveLayer(" + Sens + ");", 30);
}

var topdiv = 0;
function handle(delta) {
	if (delta < 0)
		{
		if (topdiv > -180)
			topdiv -= 20;
		}
	else
		if (topdiv <= -10)
			topdiv += 20;
	document.getElementById("contenu").style.top = topdiv + "px";
}

function wheel(event){
	var delta = 0;
	if (!event) event = window.event;
	if (event.wheelDelta) {
		delta = event.wheelDelta/120; 
		if (window.opera) delta = -delta;
	} else if (event.detail) {
		delta = -event.detail/3;
	}
	if (delta)
		handle(delta);
		if (event.preventDefault)
				event.preventDefault();
		event.returnValue = false;
}

/* Initialization code. */
if (window.addEventListener)
	window.addEventListener('DOMMouseScroll', wheel, false);
window.onmousewheel = document.onmousewheel = wheel;