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

body {
    height: calc(100% - 20px);
    margin: 0;
    padding: 10px;
}

div {
    height: 100%;
    display: flex;
    align-items: center;
    justify-content: center;
}

img {
    display: block;
    max-width: 100%;
}