var standardY;
var boxId=  'floatdiv';
var box;
window.addEvent('domready',function(){
	box = $(boxId);
	standardY = box.getPosition().y;
	box.fx = new Fx.Tween(box,{link:'cancel'});
})
window.addEvent('scroll',function(){
	if(window.getScrollTop()>standardY)
	{
		box.fx.start('top',(window.getScrollTop()-standardY));
	}
	if(window.getScrollTop()<=standardY)
		box.fx.start('top',0)
})