function getWindowHeight() {
	var windowHeight = 0;
	if (typeof(window.innerHeight) == 'number') {
		windowHeight = window.innerHeight;
	}
	else {
		if (document.documentElement && document.documentElement.clientHeight) {
			windowHeight = document.documentElement.clientHeight;
		}
		else {
			if (document.body && document.body.clientHeight) {
				windowHeight = document.body.clientHeight;
			}
		}
	}
	return windowHeight;
}

function setFooter() {
	if (document.getElementById) {
		var windowHeight = getWindowHeight();
		if (windowHeight > 0) {
			var wrapperElement = document.getElementById('wrapper');
			//var contentHeight = wrapperElement.offsetHeight;
			var e1 = document.getElementById('header');
			var e2 = document.getElementById('main');
			
			//alert(e1.offsetHeight+" "+e2.offsetHeight+" / "+(e1.offsetHeight+e2.offsetHeight)+ "="+wrapperElement.offsetHeight);
			var contentHeight = e1.offsetHeight+e2.offsetHeight;
			
			//var contentHeight = wrapperElement.offsetHeight;
			var footerElement = document.getElementById('footer');
			var footerHeight  = footerElement.offsetHeight;
			
			if (windowHeight - (contentHeight + footerHeight) > 0) {
				wrapperElement.style.height = contentHeight + (windowHeight - (contentHeight + footerHeight)) + 'px';
				//footerElement.style.top = (windowHeight - (contentHeight + footerHeight)) + 'px';
				//alert('????');
			}
			else {
				wrapperElement.style.height = contentHeight+"px";
				//alert(wrapperElement.style.height+" " + contentHeight);
				footerElement.style.top = '0px';
			}
		}
	}
}
window.onresize = function() {
	setFooter();
}