html {
    width: 100%;
    height: 100%;
}

body {
    width: 100%;
    height: 100%;
    margin: 0px;
    position: relative;
}

div.shadow {
    position: absolute;
    max-width: 45%;
    max-height: 45%;
    top: 50%;
    left: 50%;
    overflow: visible;
}

img.logo {
    position: relative;
    max-width: 100%;
    max-height: 100%;
    margin-top: -50%;
    margin-left: -50%;
}