:root {
  --bg: #050208;
}

.piece-no-need-to-know * {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
}

/* The scrub range. Height is large relative to the viewport so that a full
   pass through all chapters corresponds to a comfortable amount of scroll
   travel. The piece ends on the resting frame, holding there. */
.piece-no-need-to-know .scroll-track {
  position: relative;
  height: 600vh;
  background: var(--bg);
}

.piece-no-need-to-know .pinned {
  position: sticky;
  top: 0;
  height: 100vh;
  width: 100%;
  overflow: hidden;
  background: var(--bg);
  display: flex;
  align-items: center;
  justify-content: center;
}

.piece-no-need-to-know #scene {
  display: block;
  width: 100%;
  height: 100%;
}

/* A caption card overlaid on the pinned graphic, near the bottom of the
   viewport. Its heading/body text is swapped by script.js as t crosses
   each chapter boundary, so the explanation progresses alongside the
   graphic instead of arriving as one block of text after it. */
.piece-no-need-to-know .legend {
  position: absolute;
  left: 50%;
  bottom: 6%;
  transform: translateX(-50%);
  width: min(560px, 86vw);
  background: rgba(5, 2, 8, 0.78);
  border: 1px solid rgba(184, 255, 250, 0.22);
  border-radius: 12px;
  padding: 1rem 1.25rem 1.15rem;
  pointer-events: none;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
}

.piece-no-need-to-know .legend h3 {
  color: #9fe8db;
  font-size: 1rem;
  font-weight: 600;
  margin: 0 0 0.4rem;
}

.piece-no-need-to-know .legend p {
  color: #cdd3da;
  font-size: 0.92rem;
  line-height: 1.55;
  margin: 0;
}