var glider;
var aktiv;
var pos;
var stage = 0;
var gt;

function getWinHeight() {
	var winHt = 0;
	if (window.innerHeight) winHt = window.innerHeight-18;
	else if (document.documentElement &&
document.documentElement.clientHeight) 
		winHt = document.documentElement.clientHeight;
	else if (document.body && document.body.clientHeight) 
		winHt = document.body.clientHeight;
	return winHt;
}

function gliderInit() {
	glider = document.getElementById('bottom_glider');

	aktiv = window.setInterval("doTimeout()", 20);

	pos = getWinHeight()-300;

	gt = new Date().getTime();
}

function doTimeout() {
	
	var dur = new Date().getTime() - gt;

	glider.height = (Math.sin((dur/100))+2)*20*(1-(dur/5000))+29;

	if (dur > 5000)
		window.clearInterval(aktiv);
}