body {
    position: fixed;
    background: #555;
    top: 10%;
    left: 10%;
    right: 10%;
    bottom: 10%;
    margin: 0;
}

html {
    background: #333;
    font-family: DejaVu Sans Mono, monospace;
    font-size: 32px;
    color: #aaa;
}