#tuodiv {

    width: 100%;

    height: 100%;

    top: 0;

    left: 0;

    background: url(images/1900x953.png) no-repeat center top;

    position: fixed;

    z-index: -1;

    -webkit-background-size: cover;

    -moz-background-size: cover;

    -o-background-size: cover;

    background-size: cover;

}