html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    background: #181818;
}
html, body, * {
    box-sizing: border-box;
}
#sketch {
    width: 100%;
    height: 100%;
    display: grid;
    place-items: center;
}
svg {
    display: block;
    overflow: hidden;
    width: min(100vh, 100vw);
    height: min(100vh, 100vw);
    max-height: 640px;
    max-width: 640px;
}