body, html {
    height: 100%;
    margin: 0;
    padding: 0;
}
body {
    background-color: #eeeeee;
}
#content {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}
img.logo {
    display: block;
    max-width: 70%;
    height: auto;
}