body                    { background:white;
                          width:100%; height:100%;
                          padding:0px; margin:0px; }

div.logo                { background:url( "/gfx/logo.png" ); background-repeat:no-repeat;
                          width:300px; height:70px;
                          position:absolute;
                          top:calc( 50% - 35px ); left:calc( 50% - 150px ); }