/* roulang page: index */
:root {
      --primary: #0EA5E9;
      --accent: #F97316;
      --bg: #F8FAFC;
      --glass-bg: rgba(255, 255, 255, 0.85);
      --glow: 0 0 24px rgba(14, 165, 233, 0.5), 0 4px 12px rgba(14, 165, 233, 0.3);
      --text: #0F172A;
      --text-soft: #475569;
      --border-light: rgba(14, 165, 233, 0.1);
      --card-shadow: 0 8px 32px rgba(14, 165, 233, 0.08);
      --card-hover-shadow: 0 12px 40px rgba(14, 165, 233, 0.15);
      --radius-card: 20px;
      --radius-btn: 14px;
      --radius-tag: 8px;
    }

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

    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans SC", system-ui, sans-serif;
      background-color: var(--bg);
      color: var(--text);
      line-height: 1.7;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 1.5rem;
    }

    /* 导航栏 */
    .navbar {
      position: sticky;
      top: 0;
      z-index: 100;
      background: rgba(255, 255, 255, 0.85);
      backdrop-filter: blur(20px);
      -webkit-backdrop-filter: blur(20px);
      border-bottom: 1px solid var(--border-light);
      transition: background 0.3s ease;
    }

    .navbar.scrolled {
      background: rgba(255, 255, 255, 0.98);
    }

    .nav-link {
      color: var(--text);
      font-weight: 500;
      transition: color 0.2s;
      text-decoration: none;
    }

    .nav-link:hover {
      color: var(--primary);
    }

    .btn-primary-sm {
      background: var(--primary);
      color: white;
      padding: 0.5rem 1.25rem;
      border-radius: var(--radius-btn);
      font-weight: 600;
      box-shadow: 0 0 12px rgba(14, 165, 233, 0.4);
      transition: all 0.25s ease;
      border: none;
      cursor: pointer;
      text-decoration: none;
      display: inline-block;
    }

    .btn-primary-sm:hover {
      box-shadow: 0 0 20px rgba(14, 165, 233, 0.6);
      transform: scale(1.03);
    }

    .mobile-menu {
      display: none;
    }

    /* Hero */
    .hero {
      min-height: 90vh;
      background: linear-gradient(135deg, #0C1929 0%, #0F2340 40%, #0A1628 100%);
      display: flex;
      align-items: center;
      position: relative;
      overflow: hidden;
    }

    .hero::before {
      content: "";
      position: absolute;
      width: 100%;
      height: 100%;
      background: radial-gradient(circle at 30% 40%, rgba(14, 165, 233, 0.15) 0%, transparent 60%);
      pointer-events: none;
    }

    .particle {
      position: absolute;
      width: 4px;
      height: 4px;
      background: rgba(255, 255, 255, 0.7);
      border-radius: 50%;
      animation: float 6s infinite ease-in-out;
      box-shadow: 0 0 10px var(--primary);
    }

    @keyframes float {
      0%, 100% { transform: translateY(0) scale(1); opacity: 0.4; }
      50% { transform: translateY(-30px) scale(1.8); opacity: 0.9; }
    }

    .hero-title {
      font-size: 48px;
      font-weight: 700;
      line-height: 1.15;
      letter-spacing: -0.5px;
      color: white;
    }

    .hero-sub {
      color: rgba(255, 255, 255, 0.85);
      font-size: 18px;
      margin-top: 1rem;
    }

    .btn-glow {
      background: var(--primary);
      box-shadow: var(--glow);
      border-radius: var(--radius-btn);
      padding: 0.9rem 2.2rem;
      font-weight: 600;
      color: white;
      transition: all 0.25s ease;
      border: none;
      cursor: pointer;
      text-decoration: none;
      display: inline-block;
    }

    .btn-glow:hover {
      box-shadow: 0 0 32px rgba(14, 165, 233, 0.7);
      transform: scale(1.03);
    }

    .btn-outline {
      border: 2px solid rgba(255, 255, 255, 0.7);
      color: white;
      backdrop-filter: blur(4px);
      border-radius: var(--radius-btn);
      padding: 0.9rem 2.2rem;
      font-weight: 600;
      background: transparent;
      transition: all 0.25s ease;
      text-decoration: none;
      display: inline-block;
    }

    .btn-outline:hover {
      background: rgba(255, 255, 255, 0.1);
      border-color: white;
      transform: scale(1.03);
    }

    /* 玻璃卡片 */
    .glass-card {
      background: var(--glass-bg);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border: 1px solid rgba(14, 165, 233, 0.15);
      box-shadow: var(--card-shadow);
      border-radius: var(--radius-card);
      transition: all 0.3s ease;
    }

    .glass-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--card-hover-shadow);
      border-color: rgba(14, 165, 233, 0.3);
    }

    .section-title {
      font-size: 36px;
      font-weight: 700;
      line-height: 1.3;
      color: var(--text);
      margin-bottom: 1rem;
    }

    .data-number {
      font-family: "DIN Alternate", "SF Mono", "Roboto Mono", monospace;
      font-size: 48px;
      font-weight: 700;
      color: var(--accent);
    }

    /* FAQ手风琴 */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 1.2rem 0;
      cursor: pointer;
    }

    .faq-question {
      font-weight: 600;
      display: flex;
      align-items: center;
      gap: 0.5rem;
      color: var(--text);
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.35s ease, padding 0.35s ease;
      color: var(--text-soft);
      padding-left: 1.8rem;
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-top: 0.8rem;
    }

    .faq-item.active .faq-question i {
      color: var(--accent);
    }

    .download-bar {
      background: linear-gradient(135deg, #0EA5E9 0%, #0284C7 100%);
    }

    .footer {
      background: #0F172A;
      color: #94A3B8;
    }

    .footer a {
      color: #CBD5E1;
      transition: color 0.2s;
    }

    .footer a:hover {
      color: white;
    }

    @media (max-width: 768px) {
      .hero-title {
        font-size: 36px;
      }
      .section-title {
        font-size: 30px;
      }
      .data-number {
        font-size: 40px;
      }
      .mobile-menu {
        display: block;
      }
      .desktop-nav {
        display: none;
      }
    }