:root {
  color-scheme: dark;

  --bg: #07101b;
  --bg-deep: #050a11;
  --panel: #0b1725;
  --gold: #d2aa55;
  --gold-soft: #ead18f;
  --vermilion: #a94736;
  --ink: #f4f0e7;
  --ink-dim: rgba(244, 240, 231, 0.68);
  --line: rgba(234, 209, 143, 0.18);

  --serif: "Songti SC", "STSong", "Noto Serif CJK SC", "Source Han Serif SC", serif;
  --sans: "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", system-ui, sans-serif;

  font-family: var(--sans);
  color: var(--ink);
  background: var(--bg);
}

* {
  box-sizing: border-box;
}

html {
  background: var(--bg);
  scroll-behavior: auto;
}

body {
  margin: 0;
  min-width: 320px;
  overflow-x: hidden;
  background: var(--bg);
}

a {
  color: inherit;
}

button,
input,
textarea,
select {
  font: inherit;
}

/* =========================
   滚动影像
   ========================= */

.video-scroll {
  position: relative;
  height: var(--story-height, 980vh);
}

.stage {
  --caisson-detail: 0;

  position: sticky;
  top: 0;
  width: 100%;
  height: 100vh;
  height: 100svh;
  overflow: hidden;
  isolation: isolate;
  contain: paint;
  background: var(--bg-deep);
}

.background-video,
.shade {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.background-video {
  z-index: -3;
  display: block;
  object-fit: cover;
  object-position: center;
  opacity: 1;
  pointer-events: none;
  transform: translateZ(0);
  transition: opacity 260ms ease;
}

.shade {
  z-index: -2;
  pointer-events: none;
  background:
    linear-gradient(
      90deg,
      rgba(2, 7, 13, 0.62) 0%,
      rgba(2, 7, 13, 0.24) 30%,
      rgba(2, 7, 13, 0.03) 58%,
      rgba(2, 7, 13, 0.22) 100%
    ),
    radial-gradient(
      circle at 50% 42%,
      transparent 28%,
      rgba(0, 0, 0, 0.16) 70%,
      rgba(0, 0, 0, 0.52) 100%
    ),
    linear-gradient(
      180deg,
      rgba(0, 0, 0, 0.42) 0%,
      transparent 28%,
      transparent 64%,
      rgba(0, 0, 0, 0.52) 100%
    );
}

.stage[data-scene="base"] .shade {
  background:
    linear-gradient(90deg, rgba(2, 7, 13, 0.28), rgba(2, 7, 13, 0.06) 55%, rgba(2, 7, 13, 0.5)),
    linear-gradient(180deg, rgba(0, 0, 0, 0.34), transparent 46%, rgba(0, 0, 0, 0.42));
}

.stage[data-scene="caisson"] .shade,
.stage[data-scene="final"] .shade {
  background:
    radial-gradient(circle at 50% 46%, transparent 20%, rgba(0, 0, 0, 0.16) 64%, rgba(0, 0, 0, 0.56) 100%),
    linear-gradient(180deg, rgba(0, 0, 0, 0.34), transparent 34%, rgba(0, 0, 0, 0.42));
}

/* =========================
   官网式页头
   ========================= */

.site-header {
  position: absolute;
  z-index: 10;
  top: 0;
  right: 0;
  left: 0;

  min-height: 5rem;
  padding: 0 clamp(1.25rem, 4vw, 4.5rem);

  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;

  border-bottom: 1px solid var(--line);
  background: linear-gradient(to bottom, rgba(3, 9, 17, 0.76), rgba(3, 9, 17, 0.06));
  backdrop-filter: blur(8px);
}

.site-brand,
.footer-brand {
  display: inline-flex;
  align-items: center;
  gap: 0.9rem;
  text-decoration: none;
}

.site-brand {
  justify-self: start;
}

.brand-seal {
  width: 2.75rem;
  height: 2.75rem;
  display: grid;
  place-items: center;
  border: 1px solid rgba(210, 170, 85, 0.72);
  color: var(--gold-soft);
  font-family: var(--serif);
  font-size: 0.88rem;
  letter-spacing: 0.08em;
}

.brand-copy {
  display: flex;
  flex-direction: column;
  gap: 0.12rem;
}

.brand-copy strong {
  font-family: var(--serif);
  font-size: 1.02rem;
  letter-spacing: 0.26em;
}

.brand-copy small {
  color: rgba(244, 240, 231, 0.52);
  font-size: 0.56rem;
  letter-spacing: 0.14em;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: clamp(1.4rem, 3vw, 3.2rem);
}

.site-nav a,
.header-action {
  color: rgba(244, 240, 231, 0.76);
  font-size: 0.79rem;
  letter-spacing: 0.12em;
  text-decoration: none;
}

.site-nav a {
  position: relative;
}

.site-nav a::after {
  content: "";
  position: absolute;
  right: 0;
  bottom: -0.62rem;
  left: 0;
  height: 1px;
  background: var(--gold);
  transform: scaleX(0);
  transform-origin: center;
  transition: transform 180ms ease;
}

.site-nav a:hover::after,
.site-nav a:focus-visible::after {
  transform: scaleX(1);
}

.header-action {
  justify-self: end;
  padding: 0.68rem 0.95rem;
  border: 1px solid rgba(210, 170, 85, 0.45);
  transition: color 180ms ease, border-color 180ms ease, background 180ms ease;
}

.header-action:hover,
.header-action:focus-visible {
  color: var(--gold-soft);
  border-color: rgba(210, 170, 85, 0.8);
  background: rgba(210, 170, 85, 0.08);
}

/* =========================
   文案
   ========================= */

.copy {
  position: absolute;
  z-index: 2;
  left: clamp(1.4rem, 5vw, 5.5rem);
  right: clamp(1.4rem, 8vw, 8rem);
  max-width: 39rem;
  opacity: var(--active, 0);
  transform: translate3d(0, calc((1 - var(--active, 0)) * 1.4rem), 0);
  pointer-events: none;
  will-change: opacity, transform;
  text-shadow: 0 2px 18px rgba(0, 0, 0, 0.68), 0 1px 3px rgba(0, 0, 0, 0.78);
}

.copy-intro {
  bottom: clamp(5.7rem, 14vh, 9.5rem);
}

.copy-explode,
.copy-columns {
  top: clamp(6rem, 16vh, 10rem);
}

.copy-base {
  top: clamp(5.8rem, 15vh, 9rem);
  left: auto;
  right: clamp(5.5rem, 9vw, 9rem);
  text-align: right;
}

.copy-base .body,
.copy-final .body {
  margin-left: auto;
}

.copy-caisson {
  top: clamp(5.8rem, 15vh, 9rem);
}

.copy-final {
  top: clamp(5.3rem, 14vh, 8.5rem);
  left: auto;
  right: clamp(5.5rem, 9vw, 9rem);
  max-width: 35rem;
  text-align: right;
}

.eyebrow {
  margin: 0 0 0.9rem;
  color: var(--gold);
  font-size: clamp(0.72rem, 1vw, 0.88rem);
  font-weight: 500;
  line-height: 1.5;
  letter-spacing: 0.2em;
}

h1,
h2,
p {
  text-wrap: pretty;
}

h1 {
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(4rem, 13vw, 11rem);
  font-weight: 700;
  line-height: 0.95;
  letter-spacing: 0.08em;
}

.copy-intro .lede {
  margin: 1.15rem 0 0;
  color: var(--gold-soft);
  font-family: var(--serif);
  font-size: clamp(1rem, 2vw, 1.5rem);
  line-height: 1.6;
  letter-spacing: 0.12em;
}

h2 {
  margin: 0;
  font-family: var(--serif);
  font-size: clamp(2.25rem, 5vw, 5rem);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: 0.045em;
}

.copy .body {
  max-width: 34em;
  margin: 1.2rem 0 0;
  color: var(--ink-dim);
  font-size: clamp(0.94rem, 1.35vw, 1.16rem);
  line-height: 1.85;
  letter-spacing: 0.03em;
}

/* =========================
   节点与停顿提示
   ========================= */

.story-rail {
  position: absolute;
  z-index: 5;
  top: 50%;
  right: clamp(1rem, 2.4vw, 2.4rem);
  display: flex;
  flex-direction: column;
  gap: 0.38rem;
  transform: translateY(-50%);
}

.story-node {
  --node-progress: 0;

  position: relative;
  min-width: 5.5rem;
  padding: 0.58rem 0.7rem;
  display: grid;
  grid-template-columns: 1.35rem 1fr;
  align-items: center;
  gap: 0.5rem;

  border: 0;
  border-right: 1px solid rgba(244, 240, 231, 0.22);
  color: rgba(244, 240, 231, 0.4);
  background: transparent;
  text-align: left;
  cursor: pointer;
  transition: color 160ms ease, border-color 160ms ease, background 160ms ease;
}

.story-node::after {
  content: "";
  position: absolute;
  top: 0;
  right: -1px;
  bottom: 0;
  width: 2px;
  background: var(--gold);
  transform: scaleY(var(--node-progress));
  transform-origin: top;
}

.story-node:hover,
.story-node:focus-visible,
.story-node.is-active {
  color: var(--ink);
  border-color: rgba(210, 170, 85, 0.62);
  background: rgba(5, 12, 20, 0.24);
}

.node-index {
  color: var(--gold);
  font-size: 0.61rem;
  letter-spacing: 0.08em;
}

.node-name {
  font-family: var(--serif);
  font-size: 0.78rem;
  letter-spacing: 0.12em;
}

.hold-cue {
  --hold-active: 0;
  --hold-progress: 0;

  position: absolute;
  z-index: 6;
  right: clamp(5.5rem, 9vw, 9rem);
  bottom: 2.15rem;
  width: min(16rem, 34vw);
  opacity: var(--hold-active);
  transform: translateY(calc((1 - var(--hold-active)) * 0.7rem));
  transition: opacity 140ms linear, transform 140ms linear;
  pointer-events: none;
}

.hold-cue-label {
  display: block;
  margin-bottom: 0.52rem;
  color: rgba(244, 240, 231, 0.62);
  font-size: 0.67rem;
  letter-spacing: 0.14em;
  text-align: right;
}

.hold-cue-track {
  position: relative;
  display: block;
  width: 100%;
  height: 1px;
  overflow: hidden;
  background: rgba(244, 240, 231, 0.18);
}

.hold-cue-progress {
  position: absolute;
  inset: 0;
  background: var(--gold);
  transform: scaleX(var(--hold-progress));
  transform-origin: left;
}

.scroll-hint {
  position: absolute;
  z-index: 4;
  bottom: 2.1rem;
  left: 50%;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.62rem;
  opacity: var(--hint-active, 1);
  transform: translateX(-50%);
  pointer-events: none;
}

.scroll-hint > span:first-child {
  color: rgba(244, 240, 231, 0.62);
  font-size: 0.68rem;
  letter-spacing: 0.24em;
}

.scroll-line {
  width: 1px;
  height: 3rem;
  background: linear-gradient(to bottom, var(--gold), transparent);
  transform-origin: top;
  animation: scrollPulse 2s ease-in-out infinite;
}

@keyframes scrollPulse {
  0%, 100% { opacity: 0.3; transform: scaleY(0.55); }
  50% { opacity: 1; transform: scaleY(1); }
}

.loading-indicator {
  position: absolute;
  z-index: 7;
  right: 1.35rem;
  bottom: 1.1rem;
  color: rgba(244, 240, 231, 0.5);
  font-size: 0.67rem;
  letter-spacing: 0.12em;
  opacity: 1;
  transition: opacity 220ms ease;
}

.stage.is-ready .loading-indicator {
  opacity: 0;
}

.stage.video-error .loading-indicator {
  opacity: 1;
  color: rgba(244, 240, 231, 0.82);
}

.stage.video-error .loading-indicator::after {
  content: "失败，请检查 assets 中的视频文件";
  margin-left: 0.4rem;
}

/* =========================
   文化与页尾
   ========================= */

.heritage-section,
.site-footer {
  content-visibility: auto;
  contain-intrinsic-size: 900px;
}

.heritage-section {
  min-height: 100vh;
  min-height: 100svh;
  display: grid;
  align-items: center;
  padding: clamp(4rem, 9vw, 9rem) clamp(1.5rem, 8vw, 8rem);
  background:
    radial-gradient(circle at 18% 15%, rgba(210, 170, 85, 0.08), transparent 44%),
    linear-gradient(135deg, #0b1725, #070c13 70%);
}

.heritage-grid {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(18rem, 0.75fr);
  gap: clamp(3rem, 8vw, 9rem);
  align-items: end;
}

.heritage-title h2 {
  font-size: clamp(3rem, 7vw, 6.6rem);
}

.heritage-copy {
  padding-left: clamp(0rem, 3vw, 3rem);
  border-left: 1px solid var(--line);
}

.heritage-copy p {
  margin: 0;
  color: var(--ink-dim);
  font-size: clamp(1rem, 1.45vw, 1.28rem);
  line-height: 1.95;
  letter-spacing: 0.025em;
}

.heritage-copy p + p {
  margin-top: 1.3rem;
}

.site-footer {
  padding: clamp(4rem, 8vw, 8rem) clamp(1.5rem, 7vw, 7rem) 2rem;
  border-top: 1px solid var(--line);
  background:
    radial-gradient(circle at 15% 0%, rgba(26, 66, 96, 0.28), transparent 42%),
    #060b12;
}

.footer-heading {
  padding-bottom: 3.4rem;
  display: grid;
  grid-template-columns: 1fr minmax(20rem, 36rem);
  gap: 4rem;
  align-items: end;
  border-bottom: 1px solid rgba(244, 240, 231, 0.12);
}

.footer-brand strong {
  font-family: var(--serif);
  font-size: clamp(1.8rem, 3vw, 3rem);
  letter-spacing: 0.14em;
}

.footer-brand p,
.footer-summary {
  margin: 0.4rem 0 0;
  color: var(--ink-dim);
  line-height: 1.8;
}

.footer-grid {
  padding: 3.4rem 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr)) minmax(10rem, 0.7fr);
  gap: clamp(2rem, 5vw, 5rem);
}

.footer-grid section {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 0.72rem;
}

.footer-grid h3 {
  margin: 0 0 0.72rem;
  color: var(--gold);
  font-family: var(--serif);
  font-size: 1rem;
  letter-spacing: 0.1em;
}

.footer-grid p,
.footer-grid a {
  margin: 0;
  color: rgba(244, 240, 231, 0.6);
  font-size: 0.85rem;
  line-height: 1.7;
  text-decoration: none;
}

.footer-grid a:hover,
.footer-grid a:focus-visible {
  color: var(--gold-soft);
}

.qr-img {
  width: 7rem;
  aspect-ratio: 1;
  object-fit: cover;
  border: 1px solid rgba(244, 240, 231, 0.18);
}

.footer-bottom {
  padding-top: 1.45rem;
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  border-top: 1px solid rgba(244, 240, 231, 0.1);
  color: rgba(244, 240, 231, 0.38);
  font-size: 0.72rem;
}

.footer-bottom p {
  margin: 0;
}

.footer-bottom div {
  display: flex;
  gap: 1.4rem;
}

.footer-bottom a {
  color: inherit;
  text-decoration: none;
}

/* =========================
   响应式
   ========================= */

@media (max-width: 900px) {
  .site-header {
    grid-template-columns: 1fr auto;
  }

  .site-nav {
    display: none;
  }

  .heritage-grid,
  .footer-heading {
    grid-template-columns: 1fr;
  }

  .heritage-copy {
    padding: 2rem 0 0;
    border-top: 1px solid var(--line);
    border-left: 0;
  }

  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 720px) {
  .site-header {
    min-height: 4.5rem;
    padding: 0 1rem;
  }

  .brand-copy small {
    display: none;
  }

  .header-action {
    padding: 0.58rem 0.72rem;
    font-size: 0.72rem;
  }

  .background-video {
    object-position: center;
  }

  .shade,
  .stage[data-scene="base"] .shade,
  .stage[data-scene="caisson"] .shade,
  .stage[data-scene="final"] .shade {
    background: linear-gradient(180deg, rgba(0, 0, 0, 0.3), transparent 24%, transparent 48%, rgba(0, 0, 0, 0.76));
  }

  .copy,
  .copy-base,
  .copy-final {
    top: auto;
    right: 1.2rem;
    bottom: 5.6rem;
    left: 1.2rem;
    max-width: none;
    text-align: left;
  }

  .copy-intro {
    bottom: 6rem;
  }

  .copy-base .body,
  .copy-final .body {
    margin-left: 0;
  }

  h1 {
    font-size: clamp(3.8rem, 20vw, 7rem);
    letter-spacing: 0.04em;
  }

  h2 {
    font-size: clamp(2rem, 10vw, 3.8rem);
  }

  .copy .body {
    max-width: 31em;
    font-size: 0.9rem;
    line-height: 1.7;
  }

  .story-rail {
    top: auto;
    right: 1rem;
    bottom: 1.1rem;
    flex-direction: row;
    transform: none;
  }

  .story-node {
    min-width: 0;
    width: 2rem;
    height: 2rem;
    padding: 0;
    display: grid;
    place-items: center;
    border: 1px solid rgba(244, 240, 231, 0.22);
    border-radius: 50%;
  }

  .story-node::after,
  .node-name {
    display: none;
  }

  .hold-cue {
    right: 1.2rem;
    bottom: 4rem;
    left: 1.2rem;
    width: auto;
  }

  .footer-grid {
    grid-template-columns: 1fr;
  }

  .footer-bottom {
    flex-direction: column;
  }
}

@media (prefers-reduced-motion: reduce) {
  .scroll-line {
    animation: none;
  }

  .background-video,
  .loading-indicator,
  .site-nav a::after,
  .header-action {
    transition: none;
  }
}