.grid {
    display: grid;
    width: 100%;
  }

  main {
    place-self: center;
    overflow: hidden;
    /* max-width: 56.25em; */
    /* box-shadow: -16px 16px 23px currentcolor; */
    background: #fff;
    color: #b9b7bb;
    font: 1em/1.25 ubuntu, trebuchet ms, sans-serif;
  }

  article {
    --not-sel: min(1, max(var(--k) - var(--i), var(--i) - var(--k)));
    --sel: calc(1 - var(--not-sel));
    --sgn-sel: calc(2 * var(--sel) - 1);
    --pad: min(1.5em, 5vw);
    grid-area: 1/1;
    grid-auto-flow: column;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, 24em), 1fr));
    z-index: var(--sel);
    /* padding: var(--pad); */
    transition: z-index 0s 1s;
  }

  .c--ini {
    grid-column: 1;
  }

  .c--fin {
    grid-column-end: -1;
  }

  .fade {
    transform: translatey(calc(var(--not-sel) * 2rem));
    opacity: var(--sel);
    transition: transform 1s ease-out calc(var(--sel) * 1s),
      opacity 1s ease-in calc(var(--sel) * 1s);
  }

  .nav {
    place-self: start center;
    margin: 0.5em 0 2em;
    border: solid 1px #e0dee0;
    padding: 1em min(2.5em, 5vw);
    border-radius: 4em;
    font-weight: 700;
    text-align: center;
  }

  section {
    grid-row-end: span 3;
    clip-path: inset(calc(-1 * var(--pad)) 0);
  }

  .slice {
    --p: calc(var(--j) / var(--m));
    --s: calc((1 + var(--j)) / var(--m) * 100%);
    --mask: linear-gradient(90deg,
        transparent calc(var(--p) * 100% - 1px),
        red calc(var(--p) * 100%) var(--s),
        transparent calc(var(--s) + 1px));
    grid-area: 1/1;
    height: 610px;
    transform: translatey(calc(var(--not-sel) * (-100% - var(--pad) - 1px)));
    background: var(--img) 50% / cover;
    -webkit-mask: var(--mask);
    mask: var(--mask);
    transition: transform 1s ease-out calc((var(--sel) + var(--p)) * 1s);
  }

  .det {
    grid-auto-flow: column;
    grid-gap: 0.5em;
    place-content: end start;
    place-self: end start;
    position: relative;
    z-index: 2;
    padding: 0 1em;
    height: 0;
    line-height: 2;
    white-space: nowrap;
  }

  .det::before {
    position: absolute;
    z-index: -1;
    bottom: 0;
    height: 2em;
    width: 100%;
    background: #fff;
    content: "";
  }

  .det::after {
    content: "?";
  }