.nav_up{
	padding:2px;
	position:fixed;
	width:32px;
	height:32px;
	bottom:20px;
	opacity:0.7;
	right:30px;
	cursor: pointer;
	}
.nav_down{
	padding:2px;
	position:fixed;
	width:32px;
	height:32px;
	bottom:20px;
	opacity:0.7;
	right:66px;
	cursor: pointer;
	}