body { 
margin:0px 0px 0px 0px;
}

#box-site {
    position: absolute;
    width: 772px;
    left: 50%;
    margin: 0px 0px 0px -386px;
    border-top-width:20px;
    border-top-style:solid;
    border-top-color:#ffffff;
    border-bottom-width:200px;
    border-bottom-style:solid;
    border-bottom-color:#ffffff;
   
}