/* Picture Cube Hero — styles. Theme it by overriding the --ch-* variables on
   the mount element (or any ancestor rule with higher specificity). */
.ch {
  --ch-length: 650vh;
  --ch-bg: #0b0a0f;
  --ch-text: #ece9f5;
  --ch-muted: #9a95ab;
  --ch-accent: #d7ff3c;
  --ch-font-display: "Fraunces", Georgia, "Times New Roman", serif;
  --ch-font-body: system-ui, -apple-system, "Segoe UI", sans-serif;
  --ch-font-mono: ui-monospace, "SFMono-Regular", Menlo, monospace;
  --ch-gutter: clamp(16px, 6vw, 96px);
  position: relative;
  height: var(--ch-length);
  color: var(--ch-text);
  font-family: var(--ch-font-body);
}
.ch-sticky {
  position: sticky;
  top: 0;
  height: 100vh;
  height: 100svh;
  overflow: hidden;
}

/* The canvas repaints every frame, which gives it its own compositor layer;
   pointer-events: none keeps it from swallowing clicks meant for a fixed header. */
.ch-canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
  pointer-events: none;
  opacity: 0;
  transition: opacity 0.7s ease;
}
.ch-canvas.is-ready { opacity: 1; }
.ch-canvas[hidden], .ch-fallback[hidden] { display: none; }
.ch-fallback {
  position: absolute;
  right: 12vw;
  top: 50%;
  width: min(42vh, 36vw);
  max-width: 100%;
  aspect-ratio: 1;
  transform: translateY(-50%);
  object-fit: cover;
  border-radius: 16px;
  box-shadow: 0 30px 80px rgba(0, 0, 0, 0.55);
  pointer-events: none;
}
.ch-scrim {
  position: absolute;
  inset: 0;
  pointer-events: none;
  background: linear-gradient(
    to right,
    color-mix(in srgb, var(--ch-bg) 85%, transparent) 0%,
    color-mix(in srgb, var(--ch-bg) 40%, transparent) 30%,
    transparent 55%
  );
}

/* copy for each stop, shown while the scroll dwells on it */
.ch-copy {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  padding-inline: var(--ch-gutter);
  pointer-events: none;
}
.ch-stop {
  position: absolute;
  max-width: min(36rem, calc(100% - 2 * var(--ch-gutter)));
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.5s ease, transform 0.5s ease;
}
.ch-stop.is-visible { opacity: 1; transform: none; pointer-events: auto; }
.ch-eyebrow,
.ch-label {
  margin: 0 0 1rem;
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font: 500 0.75rem/1 var(--ch-font-mono);
  letter-spacing: 0.3em;
  text-transform: uppercase;
}
.ch-eyebrow { color: var(--ch-muted); margin-bottom: 1.5rem; }
.ch-label { color: var(--ch-accent); }
.ch-eyebrow::before,
.ch-label::before { content: ""; width: 2.5rem; height: 1px; background: currentColor; opacity: 0.6; }
.ch-name {
  margin: 0;
  font: 300 clamp(3rem, 9vw, 7.5rem) / 0.95 var(--ch-font-display);
  letter-spacing: -0.02em;
  text-wrap: balance;
}
.ch-title {
  margin: 0;
  font: 300 clamp(2.5rem, 7.5vw, 6rem) / 0.95 var(--ch-font-display);
  letter-spacing: -0.02em;
}
.ch-mark { color: var(--ch-accent); }
.ch-desc {
  margin: 1rem 0 0;
  max-width: 28rem;
  font-size: 1.125rem;
  line-height: 1.6;
  color: color-mix(in srgb, var(--ch-text) 82%, var(--ch-muted));
}
.ch-link {
  margin-top: 1.5rem;
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.7rem 1.25rem;
  border-radius: 999px;
  background: var(--ch-accent);
  color: var(--ch-bg);
  font: 600 0.875rem/1 var(--ch-font-body);
  text-decoration: none;
  transition: transform 0.2s ease;
}
.ch-link:hover { transform: translateY(-2px); }
.ch-link:focus-visible { outline: 2px solid var(--ch-text); outline-offset: 3px; }

/* chapter rail */
.ch-rail {
  position: absolute;
  right: max(16px, 1.5rem);
  top: 50%;
  transform: translateY(-50%);
  z-index: 2;
  display: flex;
  flex-direction: column;
  align-items: center;
}
.ch-rail-track,
.ch-rail-fill {
  position: absolute;
  left: 50%;
  top: 10px;
  bottom: 10px;
  width: 1px;
  pointer-events: none;
}
.ch-rail-track { transform: translateX(-50%); background: color-mix(in srgb, var(--ch-text) 18%, transparent); }
.ch-rail-fill { transform: translateX(-50%) scaleY(0); transform-origin: top; background: var(--ch-accent); }
.ch-rail-btn {
  all: unset;
  position: relative;
  width: 20px;
  height: 20px;
  display: grid;
  place-items: center;
  cursor: pointer;
  border-radius: 50%;
}
.ch-rail-btn:focus-visible { outline: 1px solid var(--ch-accent); outline-offset: 2px; }
.ch-rail-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: color-mix(in srgb, var(--ch-text) 30%, transparent);
  transition: transform 0.3s ease, background 0.3s ease;
}
.ch-rail-btn:hover .ch-rail-dot { transform: scale(1.25); background: color-mix(in srgb, var(--ch-text) 60%, transparent); }
.ch-rail-btn.is-active .ch-rail-dot { transform: scale(1.25); background: var(--ch-accent); }
.ch-rail-name {
  position: absolute;
  right: 100%;
  margin-right: 0.5rem;
  white-space: nowrap;
  font: 500 0.625rem/1 var(--ch-font-mono);
  letter-spacing: 0.25em;
  text-transform: uppercase;
  color: var(--ch-muted);
  opacity: 0;
  transition: opacity 0.3s ease;
  pointer-events: none;
}
.ch-rail-btn:hover .ch-rail-name,
.ch-rail-btn:focus-visible .ch-rail-name,
.ch-rail-btn.is-active .ch-rail-name { opacity: 1; }
.ch-rail-btn.is-active .ch-rail-name { color: var(--ch-accent); }

.ch-hint {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  font: 500 0.75rem/1 var(--ch-font-mono);
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: var(--ch-muted);
  transition: opacity 0.5s ease;
  pointer-events: none;
}
.ch-hint span { display: inline-block; animation: ch-pulse 2s ease-in-out infinite; }
@keyframes ch-pulse { 50% { opacity: 0.4; } }

/* portrait: cube high, copy low */
@media (max-aspect-ratio: 1/1) {
  .ch-copy { align-items: flex-end; padding-bottom: 14vh; }
  .ch-scrim {
    background: linear-gradient(
      to top,
      color-mix(in srgb, var(--ch-bg) 95%, transparent) 0%,
      color-mix(in srgb, var(--ch-bg) 70%, transparent) 40%,
      transparent 62%
    );
  }
  .ch-fallback { right: 50%; top: 30%; width: 62vw; transform: translate(50%, -50%); }
}

@media (prefers-reduced-motion: reduce) {
  .ch-canvas, .ch-stop, .ch-rail-dot, .ch-rail-name, .ch-hint, .ch-link { transition: none; }
  .ch-hint span { animation: none; }
}