   /* In browsers that don't support dvh, use the large-small-dynamic-viewport-units-polyfill */
      :root {
        --nav-top: calc((100 * var(--1dvh)) - var(--nav-total-height));
      }
    }
  </style>

  <style id="theGrayscaleStyle" media="only x">
    /* Firefox doesn't seem to like applying filter: grayscale() to
     * the entire body, so we apply individually.
     */
    img, svg, video,
    input[type="checkbox"], input[type="radio"],
    .inline-emoji, .theme-preview, .account-profile {
     