function showPopup(id) {
	hidePopups();
	var popup = document.getElementById(id);
        var top = parseInt((document.documentElement.clientHeight - popup.offsetHeight) / 2 * 0.7) + document.documentElement.scrollTop
        var left = parseInt((document.documentElement.offsetWidth - popup.offsetWidth) / 2) + document.documentElement.scrollLeft
	if (top < 0) top = 0;
	if (left < 0) left = 0;
	popup.style.top = top + "px";
	popup.style.left = left + "px";
}

function hidePopups() {
	var popup;
	popup = document.getElementById("tellAFriendPopup");
	popup.style.left = -10000 + "px";
	popup = document.getElementById("newsletterSignup");
	popup.style.left = -10000 + "px";
	popup = document.getElementById("purchaseAgreementPopup");
	popup.style.left = -10000 + "px";
	popup = document.getElementById("benefitsPopup");
	popup.style.left = -10000 + "px";
}