:root {
    --bg: #05060a;
    --text: rgba(255, 255, 255, 0.92);
    --muted: rgba(255, 255, 255, 0.68);
    --border: rgba(255, 255, 255, 0.12);
  }
  
  * { box-sizing: border-box; }
  html, body { height: 100%; }
  
  body {
    margin: 0;
    font-family: ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Helvetica, Arial,
      "Apple Color Emoji", "Segoe UI Emoji";
    background: var(--bg);
    color: var(--text);
  }
  
  /* ✅ 全局背景：跨屏的关键 */
  .bg {
    position: fixed;
    inset: 0;
    z-index: 0;
    overflow: hidden;
    pointer-events: none; /* 不抢点击 */
  }
  
  .spline {
    width: 100%;
    height: 100%;
    display: block;
  }
  
  /* 蒙层（你要更淡就调 rgba 最后一个数字） */
  .bg__overlay {
    position: absolute;
    inset: 0;
    background: radial-gradient(
      1200px 700px at 30% 30%,
      rgba(0,0,0,0.00),
      rgba(0,0,0,0.00) 70%,
      rgba(0,0,0,0.00)
    );
  }
  
  /* 顶部导航 */
  .nav {
    position: fixed;
    top: 0; left: 0; right: 0;
    z-index: 50;
    backdrop-filter: blur(10px);
    background: rgba(5, 6, 10, 0.35);
    border-bottom: 1px solid var(--border);
  }
  
  .nav__inner {
    max-width: 1120px;
    margin: 0 auto;
    padding: 14px 18px;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
  }
  
  .brand { font-weight: 700; letter-spacing: 0.2px; }
  
  .links { display: flex; gap: 16px; }
  .links a {
    color: var(--muted);
    text-decoration: none;
    font-size: 14px;
  }
  .links a:hover { color: var(--text); }
  
  /* ✅ 内容层在背景之上 */
  .page {
    position: relative;
    z-index: 1;
  }
  
  /* Hero */
  .hero {
    min-height: 100vh; /* 首屏 */
    border-bottom: 1px solid var(--border);
  }
  
  .hero__content {
    max-width: 1120px;
    margin: 0 auto;
    padding: 650px 18px 60px; /* 你要更靠前就减小 80 */
    min-height: 100vh;
  
    display: flex;
    flex-direction: column;
    justify-content: flex-start;
    gap: 14px;
  }
  
  .hero__spacer {
    height: 100vh; /* ✅ 这里控制“动效滚动长度”——想更长就加大 */
  }
  
  /* 文案 */
  .eyebrow {
    color: var(--muted);
    text-transform: uppercase;
    letter-spacing: 0.14em;
    font-size: 12px;
    margin: 0 0 6px;
  }
  
  h1 {
    margin: 0;
    font-size: clamp(34px, 4.2vw, 62px);
    line-height: 1.05;
    letter-spacing: -0.02em;
  }
  
  .sub {
    margin: 0;
    max-width: 58ch;
    color: var(--muted);
    font-size: 16px;
    line-height: 1.6;
  }
  
  .cta { display: flex; gap: 12px; margin-top: 10px; flex-wrap: wrap; }
  
  .btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    padding: 12px 16px;
    border-radius: 999px;
    border: 1px solid var(--border);
    text-decoration: none;
    color: var(--text);
    font-weight: 600;
    font-size: 14px;
    background: rgba(255,255,255,0.04);
  }
  .btn:hover { background: rgba(255,255,255,0.08); }
  
  .btn--primary { background: rgba(255,255,255,0.16); }
  .btn--primary:hover { background: rgba(255,255,255,0.22); }
  
  .scrollhint {
    margin-top: 26px;
    color: rgba(255,255,255,0.55);
    font-size: 13px;
  }
  
  /* 后续 section */
  .next {
    padding: 90px 0;
    border-top: 1px solid var(--border);
  }
  
  .container {
    max-width: 1120px;
    margin: 0 auto;
    padding: 0 18px;
  }
  
  /* ✅ 透明：能继续看到 Spline 背景 */
  .next--transparent {
    background: rgba(5, 6, 10, 0.10);
  }
  
  /* ✅ 实底：如果你想从某一屏开始“切走背景”，用这个 */
  .next--solid {
    background: rgba(5, 6, 10, 0.85);
  }