:root {
  color-scheme: dark;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: #050507;
  --accent: #7db8ff;
  --accent-dim: rgba(125, 184, 255, 0.45);
  --text-primary: #f5f7fa;
  --text-secondary: rgba(245, 247, 250, 0.68);
  --text-tertiary: rgba(245, 247, 250, 0.38);
  --border: rgba(255, 255, 255, 0.12);
}

* { box-sizing: border-box; }

/* 全局隐藏滚动条（保留滚动功能） */
html {
  scrollbar-width: none; /* Firefox */
  -ms-overflow-style: none; /* IE / Edge */
}
html::-webkit-scrollbar {
  width: 0;
  height: 0;
  display: none;
}

body { margin: 0; background: #050507; color: var(--text-primary); overflow-x: hidden; }
a { color: inherit; text-decoration: none; }

/* ================================================================
   第一屏：横向拖动控制视频
   ================================================================ */
.video-hero {
  position: sticky;
  top: 0;
  z-index: 1;
  isolation: isolate;
  width: 100%;
  height: 100svh;
  min-height: 34rem;
  overflow: hidden;
  touch-action: pan-y;
  user-select: none;
}

.video-hero__media,
.video-hero__shade,
.video-hero__grain {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.video-hero__media { object-fit: cover; pointer-events: none; }

/* 双向渐变遮罩：上下压暗 + 左右轻微压暗，保证文字可读 */
.video-hero__shade {
  z-index: 1;
  background:
    linear-gradient(180deg, rgba(5,5,7,0.72) 0%, rgba(5,5,7,0.08) 28%, rgba(5,5,7,0.08) 58%, rgba(5,5,7,0.88) 100%),
    linear-gradient(90deg, rgba(5,5,7,0.5) 0%, rgba(5,5,7,0.04) 48%, rgba(5,5,7,0.32) 100%);
}

/* 胶片颗粒纹理，增加质感 */
.video-hero__grain {
  z-index: 1;
  opacity: 0.045;
  pointer-events: none;
  background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)'/%3E%3C/svg%3E");
}

/* ---- 顶部导航 ---- */
.site-nav {
  position: absolute; z-index: 3; top: 0; left: 0;
  display: grid; grid-template-columns: 1fr auto 1fr; align-items: center;
  width: 100%; padding: 1.75rem clamp(1.5rem, 4vw, 4.5rem);
  font-size: .68rem; font-weight: 650; letter-spacing: .1em;
}
.site-nav__left { display: flex; align-items: center; gap: 0; }
.site-nav__brand {
  font-size: 1.05rem; font-weight: 700; letter-spacing: 0.14em;
  color: #fff; cursor: pointer;
}
.site-nav__descriptor { margin: 0; color: var(--text-secondary); font-size: .58rem; letter-spacing: .2em; text-align: center; }
.site-nav__cta {
  justify-self: end; display: flex; align-items: center; gap: .5rem;
  color: var(--text-primary); padding: .55rem 1.1rem;
  border: 1px solid var(--border); border-radius: 100px;
  background: rgba(255,255,255,0.04); backdrop-filter: blur(10px);
  transition: all 220ms ease;
}
.site-nav__cta:hover { border-color: var(--accent-dim); background: rgba(125,184,255,0.1); color: var(--accent); }
.site-nav__cta span { font-size: .8rem; }

/* ---- 左侧垂直场景标注 ---- */
.video-hero__vertical-text {
  position: absolute; z-index: 2;
  left: clamp(1.25rem, 2.5vw, 2.5rem);
  top: 50%;
  transform: translateY(-50%) rotate(-90deg);
  transform-origin: left center;
  font-size: .52rem;
  letter-spacing: .28em;
  color: var(--text-tertiary);
  white-space: nowrap;
}

/* ---- 主标题区 ---- */
.video-hero__content {
  position: absolute; z-index: 2;
  left: clamp(2rem, 7vw, 8rem);
  bottom: 14%;
  max-width: 44rem;
}
.video-hero__eyebrow-row { display: flex; align-items: center; gap: .75rem; margin-bottom: 1.1rem; }
.video-hero__eyebrow-dot {
  width: 5px; height: 5px; border-radius: 50%;
  background: var(--accent); box-shadow: 0 0 12px var(--accent);
  animation: pulse-dot 2.2s ease-in-out infinite;
}
@keyframes pulse-dot { 0%, 100% { opacity: 1; } 50% { opacity: 0.35; } }
.video-hero__eyebrow { margin: 0; letter-spacing: .2em; font-size: .56rem; font-weight: 700; color: var(--accent); text-transform: uppercase; }
.video-hero h1 {
  margin: 0;
  font-size: clamp(1.9rem, 4.6vw, 4.8rem);
  line-height: 1.02;
  letter-spacing: -.06em;
  font-weight: 800;
}
.video-hero h1 em {
  font-family: Georgia, 'Times New Roman', serif;
  font-weight: 400;
  letter-spacing: -.05em;
  font-style: italic;
  color: var(--accent);
}
.video-hero__title-line {
  margin-top: 1.4rem;
  width: 48px; height: 1.5px;
  background: linear-gradient(90deg, var(--accent), transparent);
}

/* ---- 右侧宣言卡（轻量玻璃拟态，置于右下角避免遮挡主体） ---- */
.video-hero__statement {
  position: absolute; z-index: 2;
  right: clamp(1.5rem, 5vw, 6rem);
  bottom: 14%;
  width: min(17rem, 22vw);
  padding: 1.25rem 1.4rem;
  background: rgba(10, 12, 16, 0.4);
  backdrop-filter: blur(14px); -webkit-backdrop-filter: blur(14px);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 10px;
}
.video-hero__statement-label {
  display: flex; justify-content: space-between; align-items: center;
  margin-bottom: .85rem; padding-bottom: .7rem;
  border-bottom: 1px solid rgba(255,255,255,0.08);
  font-size: .5rem; letter-spacing: .16em; color: var(--text-tertiary);
}
.video-hero__statement-label span:first-child { color: var(--accent); font-weight: 700; font-size: .62rem; }
.video-hero__statement p {
  margin: 0;
  font-size: clamp(.78rem, .85vw, .86rem);
  line-height: 1.8;
  color: var(--text-secondary);
}
.video-hero__statement-meta {
  display: flex; justify-content: space-between;
  margin-top: 1rem; padding-top: .7rem;
  border-top: 1px solid rgba(255,255,255,0.08);
  font-size: .48rem; letter-spacing: .12em; color: var(--text-tertiary);
}

/* ---- 底部控制栏 ---- */
.video-hero__bottom-bar {
  position: absolute; z-index: 2;
  left: 0; bottom: 0;
  width: 100%;
  padding: 0 clamp(1.5rem, 4vw, 4.5rem) 2rem;
}
.video-hero__footer {
  margin: 0;
  font-size: .58rem; letter-spacing: .18em;
  color: var(--text-tertiary);
  display: flex; align-items: center; gap: .65rem;
}
.video-hero__footer::before {
  content: ''; width: 26px; height: 1px; background: var(--text-tertiary);
}

/* ================================================================
   第二屏：滚动控制两段视频切换
   注意：.scroll-video__sticky / .is-active / .is-exiting /
   .scroll-video__content 的 opacity+transform transition 由 JS 驱动，不可移除
   ================================================================ */
.scroll-video {
  position: relative;
  z-index: 2;
  height: 560svh;
  background: transparent;
}

.scroll-video__sticky {
  position: sticky;
  top: 0;
  height: 100svh;
  min-height: 34rem;
  overflow: hidden;
  isolation: isolate;
  background: #030508;
  opacity: 0;
  pointer-events: none;
  transition: opacity 260ms ease-out;
}

.scroll-video.is-active .scroll-video__sticky { opacity: 1; }

.scroll-video.is-exiting .scroll-video__sticky {
  position: fixed;
  inset: 0;
  height: 100svh;
  opacity: 0;
}

.scroll-video__media,
.scroll-video__shade {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

.scroll-video__media { object-fit: cover; }
.scroll-video__media--second { opacity: 0; }
.scroll-video__shade {
  z-index: 1;
  background:
    linear-gradient(180deg, rgba(3,5,8,0.62) 0%, rgba(3,5,8,0.08) 25%, rgba(3,5,8,0.08) 62%, rgba(3,5,8,0.82) 100%),
    linear-gradient(90deg, rgba(3,5,8,0.48) 0%, rgba(3,5,8,0.04) 50%, rgba(3,5,8,0.38) 100%);
}

/* ---- 章节大数字背景装饰 ---- */
.scroll-video__chapter-num {
  position: absolute; z-index: 1;
  font-size: clamp(9rem, 20vw, 22rem);
  font-weight: 900;
  line-height: 1;
  color: rgba(255,255,255,0.025);
  letter-spacing: -.08em;
  pointer-events: none;
  user-select: none;
}
.scroll-video__chapter-num--first { top: -4%; left: -1%; }
.scroll-video__chapter-num--second { bottom: -7%; right: -1%; }

/* ---- 文字面板（JS 驱动 opacity + transform） ---- */
.scroll-video__content {
  position: absolute; z-index: 2;
  max-width: 34rem;
  will-change: opacity, transform;
  transition: opacity 140ms linear, transform 140ms ease-out;
}
.scroll-video__content--first { top: 13%; left: clamp(2rem, 7vw, 8rem); }
.scroll-video__content--second { right: clamp(2rem, 7vw, 8rem); bottom: 13%; text-align: right; }

.scroll-video__eyebrow-row { display: flex; align-items: center; gap: .75rem; margin-bottom: 1.1rem; }
.scroll-video__content--second .scroll-video__eyebrow-row { justify-content: flex-end; }
.scroll-video__eyebrow-num {
  font-size: .66rem; font-weight: 800; color: var(--accent);
  padding: .25rem .55rem; border: 1px solid var(--accent-dim); border-radius: 4px;
  font-variant-numeric: tabular-nums;
}
.scroll-video__eyebrow { margin: 0; letter-spacing: .2em; font-size: .56rem; font-weight: 700; color: var(--accent); text-transform: uppercase; }

.scroll-video h2 {
  margin: 0;
  font-size: clamp(1.8rem, 4.2vw, 4.4rem);
  line-height: 1.02;
  letter-spacing: -.06em;
  font-weight: 800;
}
.scroll-video h2 em {
  font-family: Georgia, 'Times New Roman', serif;
  font-weight: 400;
  letter-spacing: -.05em;
  font-style: italic;
  color: var(--accent);
}
.scroll-video__content > p:last-of-type {
  max-width: 22rem;
  margin: 1.2rem 0 0;
  font-size: clamp(.84rem, .95vw, .94rem);
  line-height: 1.8;
  color: var(--text-secondary);
}
.scroll-video__content--second > p:last-of-type { margin-left: auto; }

/* 能力标签胶囊 */
.scroll-video__tags {
  display: flex; flex-wrap: wrap; gap: .4rem;
  margin-top: 1.2rem;
}
.scroll-video__content--second .scroll-video__tags { justify-content: flex-end; }
.scroll-video__tags span {
  font-size: .48rem; letter-spacing: .12em;
  padding: .32rem .7rem;
  border: 1px solid rgba(255,255,255,0.08); border-radius: 100px;
  color: var(--text-tertiary);
  background: rgba(255,255,255,0.02);
}

/* ---- 底部信息栏 ---- */
.scroll-video__bottom-bar {
  position: absolute; z-index: 2;
  left: 0; bottom: 0;
  width: 100%;
  padding: 0 clamp(1.5rem, 4vw, 4.5rem) 2rem;
}
.scroll-video__footer {
  margin: 0;
  display: flex; gap: 2rem;
  font-size: .58rem; letter-spacing: .18em;
  color: var(--text-tertiary);
}

/* ================================================================
   响应式
   ================================================================ */
@media (max-width: 960px) {
  .video-hero__statement { display: none; }
  .video-hero__vertical-text { display: none; }
  .scroll-video__chapter-num { display: none; }
}

@media (max-width: 640px) {
  .site-nav { padding-top: 1.25rem; grid-template-columns: 1fr auto; }
  .site-nav__descriptor { display: none; }
  .site-nav__tag { display: none; }
  .site-nav__divider { display: none; }
  .video-hero__content { bottom: 16%; left: 1.5rem; }
  .video-hero__statement { display: none; }
  .video-hero__bottom-bar {
    padding-bottom: 1.25rem;
  }
  .scroll-video__content--first { top: 11%; left: 1.5rem; }
  .scroll-video__content--second { right: 1.5rem; bottom: 11%; }
  .scroll-video__bottom-bar {
    padding-bottom: 1.25rem;
  }
  .scroll-video__footer { flex-direction: column; gap: .35rem; max-width: 15rem; line-height: 1.6; }
  .scroll-video__tags { display: none; }
}