.flotante{
    background:url('fns.png');  
    top:0;
    left:0;
    width:100%;
    height:100%;
    position:absolute;    
}
.floatcontenido{
    width:300px;
    height:130px;
    background: #fff;
    position:absolute;
    padding: 10px;
    border: 3px solid black;
    box-shadow: 0px 0px 15px 0px black;
}