body {
	margin-top		: 0px;
	margin-bottom	: 0px;
	margin-left		: 0px;
	margin-right	: 0px;
	background		: url(imagenes/Usach.jpg) no-repeat center center fixed;
	font-family		: arial, verdana, sans-serif;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
	max-width:100%;
	width:100%;
	margin-left:auto;
	margin-right:auto;	
	
}