/* ============================================================
   Chapter Presentation Deck — iPhone Safari first.
   Motion tokens are overridden per-transition from JS.
   ============================================================ */

html,
body {
  height: 100%;
  overflow: hidden;
  overscroll-behavior: none;
}

#app {
  position: fixed;
  top: 0;
  left: 0;
  z-index: 1;
  width: 100%;
  transform: translate3d(0, calc(var(--chapter, 0) * -100dvh), 0);
  transition:
    transform var(--ch-camera-ms, 880ms) var(--ch-camera-ease, cubic-bezier(0.22, 1, 0.36, 1))
    var(--ch-camera-delay, 0ms);
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

#app.is-sliding {
  will-change: transform;
}

.scene {
  height: 100dvh;
  min-height: 100dvh;
}

.chapter-veil {
  position: fixed;
  inset: 0;
  z-index: 45;
  pointer-events: none;
  opacity: 0;
  contain: layout style paint;
  backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
  transform: translate3d(0, 12vh, 0);
}

@media (prefers-reduced-motion: reduce) {
  #app {
    transition: none;
  }

  .chapter-veil {
    display: none !important;
  }
}