// display translucent cover page for login and sign up
function showCover(sectNum) {
	var obj = document.getElementById("coverPage");
	var objS = document.getElementById("coverShade");
	var objB = document.getElementById("coverBox");
	var h = window.document.body.clientHeight;
	var w = window.document.body.clientWidth;	
	var l = (w - 567) / 2;
	obj.style.height = h + "px";
	objS.style.height = h + "px";
	objB.style.left = l + "px";	
	showCoverSection(sectNum);
	obj.style.display = "block";
}

// show coverpage section
function showCoverSection(n) {
	var arrSect = getElementsByClass("coverBox", "div", "section");
	for (i = 0; i < arrSect.length; i++) {
		arrSect[i].style.display = "none";
		if (i == n) {
			arrSect[i].style.display = "block";
		}
	}
}

// close the cover page
function closeCover() {
	document.getElementById("coverPage").style.display = "none";
}