@layer structureMotion {
  :root {
    --motion-copy-duration: 420ms;
    --motion-photo-duration: 900ms;
    --motion-rule-duration: 900ms;
    --motion-reveal-duration: 1100ms;
  }
  .structure-image { overflow: hidden; }
  .motion-rule-host { position: relative; border-top-color: transparent; }
  .motion-rule { position: absolute; inset-block-start: -1px; inset-inline: 0; height: 1px; background: #b8b8b8; transform-origin: left center; pointer-events: none; }
}