body{
	margin:0;
	padding:0;
	text-align: center;
	background-color:white;
	color:black;
 }
 div#main {
	position:absolute;
	height: 600px;
	width: 800px;
	top:50%;
	left:50%;
	margin-top: -300px;
	margin-left: -400px;
 }
 a#link_arriba{
	border: none;
	position: absolute;
	top:100px;
	left:153px;
	display:block;
	width:193px;
	height:74px;
 }
 a#link_abajo{
	border: none;
	position: absolute;
	top:255px;
	left:340px;
	display:block;
	width:128px;
	height:13px;
 }

 a span{
	display:none;
 }
 img{
	border: none;
 }