/* The Fulcrum — cinematic intro (film cuts / dissolves / title cards)
   Austere literary feel. Extends scenes.css atmospheres. */

.intro-page {
  --intro-ink: var(--ink, #1a1a1a);
  --intro-bg: var(--bg, #faf9f6);
  --intro-ease: cubic-bezier(0.22, 0.61, 0.36, 1);
  --intro-cut: 120ms;
  --intro-dissolve: 900ms;
  --intro-iris: 1100ms;
  background: var(--intro-bg);
  color: var(--intro-ink);
  min-height: 100vh;
  overflow: hidden;
}

.intro-page .site-header {
  background: color-mix(in srgb, var(--intro-bg) 88%, transparent);
}

.intro-stage {
  position: relative;
  min-height: calc(100vh - var(--header-h, 3.25rem) - 4.5rem);
  max-width: 40rem;
  margin: 0 auto;
  padding: 2.5rem var(--page-pad, 1.5rem) 6rem;
}

.intro-scene {
  position: absolute;
  inset: 0;
  padding: 2.5rem var(--page-pad, 1.5rem) 5rem;
  display: flex;
  flex-direction: column;
  justify-content: center;
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
  transform: translateY(6px);
}

.intro-scene.is-active {
  position: relative;
  opacity: 1;
  visibility: visible;
  pointer-events: auto;
  transform: none;
}

/* Transition modes (applied on outgoing / incoming) */
.intro-scene.is-leaving[data-transition="cut"],
.intro-scene.is-entering[data-transition="cut"] {
  transition: opacity var(--intro-cut) linear, visibility var(--intro-cut) linear;
}

.intro-scene.is-leaving[data-transition="dissolve"],
.intro-scene.is-entering[data-transition="dissolve"],
.intro-scene.is-leaving:not([data-transition]),
.intro-scene.is-entering:not([data-transition]) {
  transition:
    opacity var(--intro-dissolve) var(--intro-ease),
    transform var(--intro-dissolve) var(--intro-ease),
    visibility var(--intro-dissolve);
}

.intro-scene.is-leaving[data-transition="iris"],
.intro-scene.is-entering[data-transition="iris"] {
  transition:
    opacity var(--intro-iris) var(--intro-ease),
    clip-path var(--intro-iris) var(--intro-ease),
    transform var(--intro-iris) var(--intro-ease),
    visibility var(--intro-iris);
}

.intro-scene.is-leaving[data-transition="iris"] {
  clip-path: circle(0% at 50% 50%);
}

.intro-scene.is-entering[data-transition="iris"] {
  clip-path: circle(0% at 50% 50%);
}

.intro-scene.is-active[data-transition="iris"],
.intro-scene.is-entering.is-active[data-transition="iris"] {
  clip-path: circle(75% at 50% 50%);
}

.intro-scene.is-leaving {
  opacity: 0;
  transform: translateY(-4px);
}

.intro-scene.is-entering {
  opacity: 0;
  transform: translateY(8px);
}

.intro-scene.is-entering.is-active {
  opacity: 1;
  transform: none;
}

/* Title cards */
.intro-scene[data-card="title"] {
  text-align: center;
}

.intro-card-label {
  font-family: var(--font-sans);
  font-size: 0.7rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin: 0 0 1.25rem;
}

.intro-card-title {
  font-size: clamp(1.85rem, 1.4rem + 2vw, 2.75rem);
  font-weight: 600;
  letter-spacing: -0.03em;
  line-height: 1.15;
  margin: 0 0 1rem;
}

.intro-card-rule {
  width: 2.75rem;
  border: none;
  border-top: 1px solid var(--rule-strong);
  margin: 0 auto 1.25rem;
  transform-origin: center;
}

.intro-scene.is-active .intro-card-rule {
  animation: scene-rule-grow 900ms var(--intro-ease) 120ms both;
}

.intro-card-sub {
  font-style: italic;
  color: var(--ink-muted);
  margin: 0;
  line-height: 1.5;
  max-width: 28rem;
  margin-inline: auto;
}

.intro-epigraph {
  text-align: center;
  font-size: clamp(1.15rem, 1rem + 0.8vw, 1.45rem);
  line-height: 1.45;
  margin: 0;
  max-width: 26rem;
  margin-inline: auto;
}

.intro-hold {
  text-align: center;
  font-size: 1.25rem;
  font-style: italic;
  margin: 0;
}

.intro-body {
  max-width: 36rem;
  margin: 0 auto;
}

.intro-body p {
  margin: 0 0 1.1em;
  line-height: 1.65;
}

.intro-body p:last-child {
  margin-bottom: 0;
}

.intro-list {
  list-style: none;
  margin: 1.25rem 0 0;
  padding: 0;
}

.intro-list li {
  padding: 0.65rem 0;
  border-bottom: 1px solid color-mix(in srgb, var(--rule) 70%, transparent);
  display: grid;
  grid-template-columns: 4.5rem 1fr;
  gap: 0.75rem;
  align-items: baseline;
}

.intro-list .n {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  letter-spacing: 0.08em;
  color: var(--ink-faint);
}

.intro-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.65rem;
  justify-content: center;
  margin-top: 1.75rem;
}

/* Chrome: progress + transport */
.intro-chrome {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 30;
  background: color-mix(in srgb, var(--intro-bg) 92%, transparent);
  backdrop-filter: blur(8px);
  border-top: 1px solid var(--rule);
  padding: 0.65rem var(--page-pad, 1.5rem) 0.85rem;
}

.intro-progress {
  height: 2px;
  background: var(--rule);
  margin-bottom: 0.65rem;
  border-radius: 1px;
  overflow: hidden;
}

.intro-progress > span {
  display: block;
  height: 100%;
  width: 0%;
  background: var(--ink);
  transition: width 400ms var(--intro-ease);
}

.intro-transport {
  max-width: 40rem;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  font-family: var(--font-sans);
  font-size: 0.75rem;
  letter-spacing: 0.04em;
  color: var(--ink-muted);
}

.intro-transport button {
  font: inherit;
  letter-spacing: inherit;
  color: var(--ink);
  background: transparent;
  border: 1px solid var(--rule);
  border-radius: 2px;
  padding: 0.45rem 0.85rem;
  cursor: pointer;
  transition: background 200ms var(--intro-ease), color 200ms var(--intro-ease), border-color 200ms;
}

.intro-transport button:hover,
.intro-transport button:focus-visible {
  border-color: var(--ink);
  background: var(--ink);
  color: var(--bg);
}

.intro-transport button:disabled {
  opacity: 0.35;
  cursor: not-allowed;
}

.intro-meta {
  text-align: center;
  flex: 1;
  min-width: 0;
}

.intro-meta strong {
  color: var(--ink);
  font-weight: 600;
}

.intro-skip {
  color: var(--ink-faint);
  text-decoration: none;
}

.intro-skip:hover {
  color: var(--ink);
  text-decoration: underline;
  text-underline-offset: 0.15em;
}

.intro-dwell {
  display: block;
  margin-top: 0.2rem;
  font-size: 0.68rem;
  color: var(--ink-faint);
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

/* Film stills — austere literary backgrounds (local PNGs; Cloudinary pending) */
.intro-scene {
  isolation: isolate;
}
.intro-scene::before {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background-color: transparent;
  background-position: center;
  background-size: cover;
  background-repeat: no-repeat;
  opacity: 0.22;
  filter: grayscale(1) contrast(1.05);
}
.intro-scene::after {
  content: "";
  position: absolute;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  background: linear-gradient(
    180deg,
    color-mix(in srgb, var(--intro-bg, var(--bg, #faf9f6)) 72%, transparent) 0%,
    color-mix(in srgb, var(--intro-bg, var(--bg, #faf9f6)) 88%, transparent) 55%,
    color-mix(in srgb, var(--intro-bg, var(--bg, #faf9f6)) 94%, transparent) 100%
  );
}
.intro-scene > * {
  position: relative;
  z-index: 1;
}
.intro-scene[data-scene-id="open"]::before { background-image: url("../assets/film/open.png"); opacity: 0.34; }
.intro-scene[data-scene-id="epigraph"]::before { background-image: url("../assets/film/epigraph.png"); }
.intro-scene[data-scene-id="hold"]::before { background-image: url("../assets/film/hold.png"); opacity: 0.28; }
.intro-scene[data-scene-id="premise"]::before { background-image: url("../assets/film/premise.png"); }
.intro-scene[data-scene-id="registers"]::before { background-image: url("../assets/film/registers.png"); }
.intro-scene[data-scene-id="part-i"]::before { background-image: url("../assets/film/part-i.png"); opacity: 0.26; }
.intro-scene[data-scene-id="part-ii"]::before { background-image: url("../assets/film/part-ii.png"); }
.intro-scene[data-scene-id="evidence-card"]::before { background-image: url("../assets/film/evidence-card.png"); }
.intro-scene[data-scene-id="ise"]::before { background-image: url("../assets/film/ise.png"); }
.intro-scene[data-scene-id="phi"]::before { background-image: url("../assets/film/phi.png"); }
.intro-scene[data-scene-id="six"]::before { background-image: url("../assets/film/six.png"); }
.intro-scene[data-scene-id="ab"]::before { background-image: url("../assets/film/ab.png"); }
.intro-scene[data-scene-id="part-iv"]::before { background-image: url("../assets/film/part-iv.png"); }
.intro-scene[data-scene-id="part-v"]::before { background-image: url("../assets/film/part-v.png"); opacity: 0.26; }
.intro-scene[data-scene-id="how"]::before { background-image: url("../assets/film/how.png"); }
.intro-scene[data-scene-id="talk"]::before { background-image: url("../assets/film/talk.png"); }
.intro-scene[data-scene-id="shop"]::before { background-image: url("../assets/film/shop.png"); }
.intro-scene[data-scene-id="begin"]::before { background-image: url("../assets/film/begin.png"); opacity: 0.28; }

.intro-page[data-scene="black"] .intro-scene::after {
  background: linear-gradient(
    180deg,
    rgba(14, 14, 14, 0.55) 0%,
    rgba(14, 14, 14, 0.78) 50%,
    rgba(14, 14, 14, 0.9) 100%
  );
}

/* Atmospheres inherited via body[data-scene] from scenes.css */
.intro-page[data-scene="black"] {
  --intro-bg: #0e0e0e;
  --intro-ink: #f2efe8;
  background: #0e0e0e;
  color: #f2efe8;
}

.intro-page[data-scene="black"] .site-header,
.intro-page[data-scene="black"] .intro-chrome {
  background: color-mix(in srgb, #0e0e0e 90%, transparent);
  border-color: #2a2a2a;
}

.intro-page[data-scene="black"] .intro-progress {
  background: #2a2a2a;
}

.intro-page[data-scene="black"] .intro-progress > span,
.intro-page[data-scene="black"] .intro-transport button:hover,
.intro-page[data-scene="black"] .intro-transport button:focus-visible {
  background: #f2efe8;
  color: #0e0e0e;
}

.intro-page[data-scene="black"] .intro-card-rule {
  border-color: #f2efe8;
}

.intro-page[data-scene="black"] .intro-transport button {
  border-color: #444;
  color: #f2efe8;
}

.intro-page[data-scene="black"] .site-mark,
.intro-page[data-scene="black"] .site-nav a {
  color: #c8c4bc;
}

@media (prefers-reduced-motion: reduce) {
  .intro-scene,
  .intro-scene.is-leaving,
  .intro-scene.is-entering,
  .intro-progress > span,
  .intro-scene.is-active .intro-card-rule {
    transition: none !important;
    animation: none !important;
    clip-path: none !important;
    transform: none !important;
  }
  .intro-scene::before {
    filter: grayscale(1);
    opacity: 0.18;
  }
}

@media (max-width: 540px) {
  .intro-list li {
    grid-template-columns: 1fr;
    gap: 0.15rem;
  }
  .intro-transport {
    flex-wrap: wrap;
  }
}

.intro-cinema .intro-scene.intro-cinema-beat.is-active {
  animation: introKen 18s ease-out forwards;
}
@keyframes introKen {
  from { background-size: 108% auto; }
  to { background-size: 100% auto; }
}
@media (prefers-reduced-motion: reduce) {
  .intro-cinema .intro-scene.intro-cinema-beat.is-active { animation: none; }
}
.intro-page.intro-epigraph-active {
  background: #050505;
}