html,
body {
    height: 100%;
    margin: 0;
}

.box {
    display: flex;
    flex-flow: column;
    height: 100%;
}


.Main{
    display: flex;
    height: 100%;
    background-image: url(images/HeaderBG.png);
    background-position: center center;
    background-repeat: repeat-x;
    background-size: contain;
}

.DerSDX{
    margin: auto;
    width: 262px;
    height: 76px;
    background-image: url(images/DerSDX.png);
    background-position: center center;
    background-repeat: no-repeat;
    background-size: contain;
}