* {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }

    html {
      scroll-behavior: auto;
    }

    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", sans-serif;
      background: #000;
      color: #f5f5f7;
      overflow-x: hidden;
    }

    /* 首屏滚动区：拉高页面，让大标题有一段「跟滚动上移」的空间 */
    .hero-scroll {
      height: 220vh;
      position: relative;
    }

    .hero-sticky {
      position: sticky;
      top: 0;
      height: 100vh;
      min-height: 520px;
      display: flex;
      align-items: center;
      justify-content: center;
      overflow: hidden;
    }

    .hero-inner {
      text-align: center;
      padding: 0 24px;
      will-change: transform, opacity;
    }

    .hero-title {
      font-size: clamp(48px, 12vw, 96px);
      font-weight: 600;
      letter-spacing: -0.03em;
      line-height: 1.05;
      margin-bottom: 0.35em;
    }

    .hero-sub {
      font-size: clamp(18px, 2.8vw, 28px);
      font-weight: 400;
      opacity: 0.88;
      max-width: 28em;
      margin: 0 auto;
      line-height: 1.35;
    }

    .after {
      min-height: 100vh;
      padding: 80px 24px 120px;
      text-align: center;
      background: linear-gradient(180deg, #000 0%, #0d0d0f 40%, #111 100%);
    }

    .after h2 {
      font-size: clamp(28px, 5vw, 44px);
      font-weight: 600;
      margin-bottom: 16px;
    }

    .after p {
      opacity: 0.65;
      font-size: 17px;
      line-height: 1.6;
      max-width: 36em;
      margin: 0 auto;
    }

    .hint {
      position: fixed;
      bottom: max(24px, env(safe-area-inset-bottom));
      left: 50%;
      transform: translateX(-50%);
      font-size: 13px;
      opacity: 0.45;
      pointer-events: none;
      white-space: nowrap;
      z-index: 2;
    }

    @media (prefers-reduced-motion: reduce) {
      .hero-inner {
        will-change: auto;
      }
    }