/* ============================================================================
   scrub-section.css — the Tenant-compliant layout contract for an embeddable
   scroll-scrub section. Namespaced entirely under `.scrub` / `--scrub-*`.

   HARD RULE: no `position: fixed` anywhere in this file, no `:root` writes.
   The pin is the browser's own `position: sticky` — the section never fights
   the host page for the viewport. See plans/specs/embeddable-scrub-section/.
   ========================================================================== */

.scrub {
  position: relative;
  isolation: isolate;
  --scrub-progress: 0;
  --scrub-accent: #8a7bb5;
  --scrub-bg: #0b0b10;
  --scrub-ink: #f5f3ef;
  --scrub-ink-soft: rgba(245, 243, 239, 0.72);
  color: var(--scrub-ink);
  background: var(--scrub-bg);
}

/* the pinned media stage — sticky, never fixed. 100dvh so iOS URL-bar
   collapse/expand never re-triggers layout (see engine's ignore-height-only). */
.scrub__stage {
  position: sticky;
  top: 0;
  height: 100dvh;
  overflow: hidden;
  z-index: 1;
}

.scrub__canvas {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  display: block;
}

.scrub__poster {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center 42%;
  opacity: 1;
  transition: opacity 0.3s ease;
}
.scrub.is-painted .scrub__poster { opacity: 0; }

/* story = the copy chapters, pulled up over the stage with a negative margin so
   each chapter pins in turn above the still-sticky media. pointer-events:none on
   the layer so it never blocks the media; individual copy cards re-enable it. */
.scrub__story {
  position: relative;
  z-index: 3;
  margin-top: -100dvh;
  pointer-events: none;
}

.scrub__chapter {
  position: relative;
  min-height: 100dvh;
}

.scrub__chapter-pin {
  position: sticky;
  top: 0;
  min-height: 100dvh;
  display: flex;
  align-items: center;
  padding: clamp(24px, 5vw, 64px);
}

.scrub__copy {
  pointer-events: auto;
  width: min(40rem, 44vw);
  opacity: 0;
  transform: translateY(16px);
  transition: opacity 0.35s ease, transform 0.35s ease;
  background: linear-gradient(180deg, rgba(11, 11, 16, 0.0) 0%, rgba(11, 11, 16, 0.55) 28%, rgba(11, 11, 16, 0.75) 100%);
  border-radius: 18px;
  padding: clamp(18px, 2.4vw, 30px);
}
.scrub__chapter.is-active .scrub__copy {
  opacity: 1;
  transform: translateY(0);
}

.scrub__eyebrow {
  display: block;
  font-weight: 700;
  font-size: 0.78rem;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--scrub-accent);
  margin: 0 0 10px;
}
.scrub__title {
  font-weight: 700;
  font-size: clamp(1.7rem, 3.4vw, 2.6rem);
  line-height: 1.08;
  margin: 0 0 12px;
}
.scrub__body {
  font-size: clamp(0.95rem, 1.1vw, 1.05rem);
  line-height: 1.55;
  color: var(--scrub-ink-soft);
  margin: 0;
  max-width: 42ch;
}
.scrub__tags {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 18px 0 0;
  padding: 0;
}
.scrub__tags li {
  font-size: 0.78rem;
  font-weight: 600;
  padding: 6px 12px;
  border-radius: 999px;
  color: var(--scrub-accent);
  border: 1px solid color-mix(in srgb, var(--scrub-accent) 40%, transparent);
  background: color-mix(in srgb, var(--scrub-accent) 14%, transparent);
}

/* progress + route rail — INSIDE the section, absolute (never fixed), scoped z-index */
.scrub__progress {
  position: absolute;
  left: 0;
  right: 0;
  top: 0;
  height: 3px;
  z-index: 4;
  background: color-mix(in srgb, var(--scrub-accent) 16%, transparent);
  pointer-events: none;
}
.scrub__progress i {
  display: block;
  height: 100%;
  width: calc(var(--scrub-progress) * 100%);
  background: var(--scrub-accent);
  transform-origin: 0 50%;
}

.scrub__route {
  position: absolute;
  right: clamp(14px, 2.4vw, 30px);
  top: 50%;
  transform: translateY(-50%);
  z-index: 4;
  display: flex;
  flex-direction: column;
  gap: 14px;
  pointer-events: none;
}
.scrub__route i {
  display: block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: color-mix(in srgb, var(--scrub-accent) 40%, transparent);
  transition: background 0.25s, transform 0.25s;
}
.scrub__route i.is-active {
  background: var(--scrub-accent);
  transform: scale(1.4);
}

/* mobile — non-pinned variant (pin fights touch momentum, see UC-04) */
@media (max-width: 860px) {
  .scrub__stage {
    position: relative;
    height: auto;
    aspect-ratio: 4 / 5;
  }
  .scrub__poster,
  .scrub__canvas {
    object-position: center 46%;
  }
  .scrub__story {
    margin-top: 0;
  }
  .scrub__chapter-pin {
    position: relative;
    min-height: auto;
    padding: 20px clamp(18px, 5vw, 32px);
  }
  .scrub__copy {
    width: 100%;
    opacity: 1;
    transform: none;
    background: none;
    padding: 0;
  }
  .scrub__route { display: none; }
}

/* reduced motion — posters only, chapters keep their min-height so copy reads
   in full, media never fetches/decodes (enforced in JS, not just here). */
@media (prefers-reduced-motion: reduce) {
  .scrub__copy {
    transition: none;
    opacity: 1;
    transform: none;
  }
  .scrub__canvas { display: none; }
}