var popup;
function initPopup() {

	popup = document.getElementById("popup");
	popup.style.height = document.getElementById("main").offsetHeight + "px"
	initScrollbars();
	popup.style.display = "none";
	popup.style.visibility = "visible";
	document.getElementById("btn-open-popup").onclick = function () {
		popup.style.display = "block";
	}
	document.getElementById("btn-close").onclick = function () {
		popup.style.display = "none";
	}
}

if (window.addEventListener) window.addEventListener("load", initPopup, false);
else if (window.attachEvent) window.attachEvent("onload", initPopup);