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

html {
    background-image: url("checkerboard.png");
    background-repeat: repeat;
    background-size: auto;

    animation: scrollBackground 20s linear infinite;
}

@keyframes scrollBackground {
    from {
        background-position: 0 0;
    }
    to {
        background-position: 450px 450px; /* adjust depending on tile size */
    }
}