/* roulang page: index */
:root {
      --primary: #1A1D2E;
      --accent-1: #00D4AA;
      --accent-2: #FF6B3D;
      --bg-light: #F7F8FA;
      --bg-dark: #0F1119;
      --text-primary: #1A1D2E;
      --text-secondary: #5A5D6E;
      --text-light: #FFFFFF;
      --text-muted: #9A9DAA;
      --border-light: rgba(26, 29, 46, 0.08);
      --shadow-card: 0 2px 12px rgba(26, 29, 46, 0.06);
      --shadow-card-hover: 0 8px 30px rgba(26, 29, 46, 0.12);
      --shadow-dark-card: 0 4px 24px rgba(0,0,0,0.25);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-tag: 6px;
      --font-sans: 'Inter', 'PingFang SC', 'Microsoft YaHei', 'Helvetica Neue', sans-serif;
      --transition-smooth: 0.25s ease;
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: var(--font-sans);
      line-height: 1.6;
      background-color: var(--bg-light);
      color: var(--text-primary);
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition-smooth);
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
      border: none;
      background: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 15px;
      padding: 12px 28px;
      transition: all var(--transition-smooth);
      white-space: nowrap;
    }
    .container {
      max-width: 1200px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 20px;
      padding-right: 20px;
    }
    section {
      padding-top: 80px;
      padding-bottom: 80px;
    }
    @media (max-width: 768px) {
      section {
        padding-top: 60px;
        padding-bottom: 60px;
      }
    }

    /* 导航 */
    #nav {
      position: sticky;
      top: 0;
      z-index: 50;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      -webkit-backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-light);
      transition: box-shadow var(--transition-smooth);
    }
    #nav.scrolled {
      box-shadow: 0 4px 20px rgba(0,0,0,0.04);
    }
    .nav-link {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-secondary);
      padding: 8px 12px;
      border-radius: 6px;
      transition: all var(--transition-smooth);
    }
    .nav-link:hover {
      color: var(--accent-1);
      background: rgba(0,212,170,0.06);
    }
    .btn-primary {
      background: var(--accent-2);
      color: white;
    }
    .btn-primary:hover {
      background: #E55A2D;
      box-shadow: 0 6px 18px rgba(255,107,61,0.3);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--accent-1);
      color: var(--accent-1);
    }
    .btn-outline:hover {
      background: rgba(0,212,170,0.1);
    }
    .btn-dark {
      background: var(--accent-1);
      color: var(--primary);
      font-weight: 600;
    }
    .btn-dark:hover {
      box-shadow: 0 0 20px rgba(0,212,170,0.4);
    }

    /* 卡片通用 */
    .card {
      background: white;
      border-radius: var(--radius-card);
      border: 1px solid var(--border-light);
      box-shadow: var(--shadow-card);
      transition: all var(--transition-smooth);
      overflow: hidden;
    }
    .card:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-card-hover);
    }
    .tag {
      display: inline-block;
      background: rgba(0,212,170,0.12);
      color: var(--accent-1);
      font-size: 13px;
      font-weight: 500;
      padding: 4px 12px;
      border-radius: var(--radius-tag);
    }
    .stat-number {
      font-family: 'Inter', sans-serif;
      font-weight: 700;
      font-size: 36px;
      line-height: 1.2;
      color: var(--accent-2);
    }
    @media (max-width: 480px) {
      .stat-number {
        font-size: 28px;
      }
    }

    /* FAQ accordion */
    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }
    .faq-question {
      cursor: pointer;
      padding: 20px 0;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 600;
      font-size: 18px;
      transition: color var(--transition-smooth);
    }
    .faq-question:hover {
      color: var(--accent-1);
    }
    .faq-icon {
      font-size: 20px;
      transition: transform 0.25s ease;
      color: var(--text-muted);
    }
    .faq-item.active .faq-icon {
      transform: rotate(45deg);
      color: var(--accent-1);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: #f9fafb;
      border-radius: 8px;
      margin-bottom: 12px;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 16px 20px;
    }

    /* 汉堡菜单 */
    .mobile-menu {
      display: none;
    }
    @media (max-width: 768px) {
      .desktop-nav-links {
        display: none;
      }
      .mobile-menu {
        display: block;
      }
    }