body {
    width: 100%;
    height: 100%;
    overflow: hidden;
    background-color: #222;
    background-image: url("https://zatzhing.me/pages/fidget/pebbles/graph.png");
    --u: min(1vw, 1vh);
    background-size: calc(10 * var(--u));
    user-select: none;
    margin: 0;
    padding: 0;
}

html {
    width: 95vw;
    height: 80vh;
    overflow:hidden;
    margin: 0;
    padding: 0;
}

rock {
    width: calc(5 * var(--u));
    aspect-ratio: 1;
    background-color: var(--col);
    border: calc(2 * var(--u)) outset var(--col);
    border-radius: 100%;
    display: block;
    position:absolute;
    left: var(--x);
    top: var(--y);
    transform: translate(-50%,-50%);
}