html {
height: 100%;
}

body {
background-color: #FFFFFF;
text-align: center;
margin: 0px;
padding: 0px;
height: 100%;

}

#box {
background-color: #FFFFFF;
background-image: url(sfondo.gif);
text-align: left;
width: 768px;
margin-top: 0px;
margin-right: auto;
margin-bottom: 0px;
margin-left: auto;
height: 100%;
}