body, html {
    margin:0;padding:0;
    height:100%;
}
.logo {
    position:   absolute;
    top:        50%;
    left:       0;
    width:      100%;
    height:     100px;
    margin-top: -50px;
    text-align: center;
    font: bold 100px Helvetica,Arial,sans-serif;
}