html, body {
	height: 100%;
	margin: 0;
	padding: 0;
}
#bg {position:fixed; top:0; left:0; width:100%; height:100%;}
#content {position:relative; z-index:1;}
html {overflow-y:hidden;}
body {overflow-y:auto;}
#bg {position:absolute; z-index:-1;}
#content {position:static;}