function overlay() {

var _docHeight = (document.height !== undefined) ? document.height : document.body.offsetHeight;

	document.getElementById("overlay").style.height = _docHeight;
	
	document.getElementById("overlay").style.display = 'block';
	document.getElementById("signIn").style.display = 'block';
	}

function closeOverlay() {
	document.getElementById("overlay").style.display = 'none';
	document.getElementById("signIn").style.display = 'none';
	}