/* roulang page: index */
:root {
      --deep-space: #1A1A2E;
      --space-navy: #16213E;
      --star-gold: #F0A500;
      --star-gold-hover: #D49200;
      --electric-cyan: #00D2FF;
      --electric-cyan-soft: rgba(0, 210, 255, 0.15);
      --bg-light: #F8F9FA;
      --card-white: #FFFFFF;
      --faq-bg: #F1F2F6;
      --text-dark: #1A1A2E;
      --text-mid: #4A4A6A;
      --text-light: #7A7A9A;
      --border-light: #E0E0E8;
      --shadow-card: 0 4px 20px rgba(0, 0, 0, 0.04);
      --shadow-hover: 0 12px 32px rgba(0, 0, 0, 0.08);
      --radius-card: 16px;
      --radius-btn: 8px;
      --radius-badge: 6px;
    }

    * {
      box-sizing: border-box;
    }

    body {
      font-family: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", system-ui, -apple-system, 'Segoe UI', sans-serif;
      margin: 0;
      background-color: var(--bg-light);
      color: var(--text-mid);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: 1200px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 1.5rem;
      padding-right: 1.5rem;
    }

    /* 导航工具栏 */
    .utility-bar {
      background-color: #0D0D1A;
      color: #A0A0B0;
      font-size: 0.75rem;
      height: 36px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      padding: 0 1.5rem;
    }

    .main-nav {
      position: sticky;
      top: 0;
      z-index: 50;
      background: rgba(13, 13, 26, 0.85);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      height: 64px;
      display: flex;
      align-items: center;
      transition: background 0.3s ease;
    }

    .logo {
      font-size: 1.5rem;
      font-weight: 700;
      color: var(--star-gold);
      display: flex;
      align-items: center;
      gap: 0.5rem;
      text-decoration: none;
    }

    .logo i {
      font-size: 1.8rem;
      color: var(--electric-cyan);
    }

    .nav-links {
      display: flex;
      gap: 2rem;
      align-items: center;
      margin-left: auto;
    }

    .nav-link {
      color: #D0D0E0;
      text-decoration: none;
      font-weight: 500;
      font-size: 0.95rem;
      position: relative;
      transition: color 0.2s;
    }

    .nav-link::after {
      content: '';
      position: absolute;
      bottom: -6px;
      left: 0;
      width: 0%;
      height: 2px;
      background: var(--star-gold);
      transition: width 0.25s ease;
    }

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

    .nav-link:hover::after {
      width: 100%;
    }

    .btn-primary {
      background: var(--star-gold);
      color: var(--deep-space);
      font-weight: 600;
      padding: 0.6rem 1.5rem;
      border-radius: var(--radius-btn);
      text-decoration: none;
      display: inline-block;
      transition: background 0.2s, transform 0.2s;
      border: none;
      cursor: pointer;
      box-shadow: 0 4px 10px rgba(240, 165, 0, 0.3);
    }

    .btn-primary:hover {
      background: var(--star-gold-hover);
      transform: scale(1.02);
    }

    .btn-outline-gold {
      border: 2px solid var(--star-gold);
      color: var(--star-gold);
      background: transparent;
      font-weight: 600;
      padding: 0.5rem 1.5rem;
      border-radius: var(--radius-btn);
      text-decoration: none;
      transition: all 0.2s;
      display: inline-block;
    }

    .btn-outline-gold:hover {
      background: rgba(240, 165, 0, 0.1);
    }

    .btn-ghost-white {
      border: 2px solid white;
      color: white;
      background: transparent;
      font-weight: 600;
      padding: 0.5rem 1.8rem;
      border-radius: var(--radius-btn);
      transition: all 0.2s;
      text-decoration: none;
      display: inline-block;
    }

    .btn-ghost-white:hover {
      background: rgba(255, 255, 255, 0.15);
    }

    .card {
      background: var(--card-white);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: transform 0.25s, box-shadow 0.3s;
      overflow: hidden;
    }

    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
    }

    .data-badge {
      background: rgba(26, 26, 46, 0.06);
      border-radius: var(--radius-badge);
      padding: 0.25rem 0.75rem;
      display: inline-flex;
      align-items: center;
      gap: 0.3rem;
      font-size: 0.8rem;
      color: var(--text-mid);
    }

    .data-badge .num {
      font-weight: 700;
      color: var(--electric-cyan);
      font-family: 'Inter', 'SF Mono', monospace;
    }

    .section-title {
      font-size: 2.2rem;
      font-weight: 600;
      color: var(--text-dark);
      margin-bottom: 0.75rem;
      line-height: 1.3;
    }

    .section-sub {
      color: var(--text-light);
      font-size: 1.1rem;
    }

    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 1rem 0;
    }

    .faq-question {
      font-weight: 600;
      font-size: 1.1rem;
      color: var(--text-dark);
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .faq-answer {
      color: var(--text-mid);
      margin-top: 0.5rem;
      display: none;
      line-height: 1.7;
    }

    .faq-item.active .faq-answer {
      display: block;
    }

    .faq-item.active {
      background-color: var(--faq-bg);
      border-radius: 8px;
      padding-left: 12px;
      padding-right: 12px;
    }

    .mobile-menu-btn {
      display: none;
      background: none;
      border: none;
      color: white;
      font-size: 1.8rem;
      cursor: pointer;
    }

    @media (max-width: 768px) {
      .nav-links {
        display: none;
        flex-direction: column;
        position: absolute;
        top: 64px;
        left: 0;
        width: 100%;
        background: rgba(13, 13, 26, 0.96);
        backdrop-filter: blur(20px);
        padding: 1.5rem;
        gap: 1.2rem;
      }
      .nav-links.active {
        display: flex;
      }
      .mobile-menu-btn {
        display: block;
        margin-left: auto;
      }
      .hero-grid {
        flex-direction: column;
      }
      .highlight-grid {
        grid-template-columns: 1fr;
      }
      .case-grid {
        columns: 1;
      }
      .plan-grid {
        flex-direction: column;
      }
      .faq-flex {
        flex-direction: column;
      }
    }

    @media (max-width: 480px) {
      .section-title {
        font-size: 1.8rem;
      }
    }