function showPopup(){
		var popup = document.getElementById("popup");
		if(popup){
			positionPopup();
			popup.style.zIndex=10000;
			popup.style.visibility = "visible";
			window.onresize = positionPopup;
			window.onscroll = positionPopup;
		}
	}
	
	function positionPopup(){
		var popup = document.getElementById("popup");
		if(popup){
			popup.style.left = ((document.body.clientWidth-parseInt(popup.style.width))/2<0) ? 0 : (document.body.clientWidth-parseInt(popup.style.width))/2+document.body.scrollLeft;
			popup.style.top = ((document.body.clientHeight-parseInt(popup.style.height))/2<0) ? 0 : (document.body.clientHeight-parseInt(popup.style.height))/2+document.body.scrollTop;
		}
	}
	
	function closePopup(){
		var popup = document.getElementById("popup");
		if(popup){
			popup.style.visibility = "hidden";
		}
	}