/* roulang page: index */
:root {
      --primary: #1A6DF5;
      --primary-dark: #1558D4;
      --accent: #FF6B35;
      --accent-dark: #E55A2B;
      --bg-warm: #F8FAFB;
      --bg-light-blue: #EEF2FF;
      --text-dark: #1E293B;
      --text-muted: #64748B;
      --text-body: #475569;
      --card-shadow: 0 4px 20px rgba(0,0,0,0.04);
      --card-shadow-hover: 0 8px 30px rgba(0,0,0,0.08);
      --border-light: #E2E8F0;
      --radius-md: 16px;
      --radius-btn: 12px;
      --radius-img: 24px;
    }
    * {
      box-sizing: border-box;
    }
    body {
      margin: 0;
      font-family: "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      background-color: var(--bg-warm);
      color: var(--text-body);
      line-height: 1.75;
      font-size: 16px;
      -webkit-font-smoothing: antialiased;
    }
    h1, h2, h3, h4 {
      color: var(--text-dark);
      font-weight: 700;
      letter-spacing: -0.02em;
    }
    h1 { font-size: 48px; line-height: 1.2; }
    h2 { font-size: 36px; line-height: 1.3; }
    h3 { font-size: 24px; line-height: 1.4; }
    @media (max-width: 768px) {
      h1 { font-size: 32px; }
      h2 { font-size: 28px; }
      h3 { font-size: 22px; }
    }
    a {
      text-decoration: none;
      color: inherit;
    }
    img {
      max-width: 100%;
      display: block;
    }
    .container {
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }
    .section-padding {
      padding: 120px 0;
    }
    @media (max-width: 768px) {
      .section-padding {
        padding: 80px 0;
      }
    }
    /* 导航 */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: white;
      border-bottom: 1px solid var(--border-light);
      height: 72px;
      z-index: 1000;
      display: flex;
      align-items: center;
    }
    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }
    .logo {
      font-weight: 800;
      font-size: 1.8rem;
      color: var(--primary);
      letter-spacing: -0.5px;
      display: flex;
      align-items: baseline;
      gap: 6px;
    }
    .logo span.domain {
      font-size: 0.75rem;
      font-weight: 400;
      color: var(--text-muted);
      margin-left: 4px;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-dark);
      position: relative;
      padding: 4px 0;
      transition: color 0.2s;
    }
    .nav-links a::after {
      content: '';
      position: absolute;
      bottom: -4px;
      left: 0;
      width: 0;
      height: 2px;
      background: var(--primary);
      transition: width 0.2s;
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .nav-links a:hover::after {
      width: 100%;
    }
    .btn-nav {
      background: var(--primary);
      color: white !important;
      padding: 8px 20px;
      border-radius: 24px;
      font-weight: 600;
      font-size: 14px;
      transition: background 0.2s;
    }
    .btn-nav:hover {
      background: var(--primary-dark);
    }
    .hamburger {
      display: none;
      font-size: 24px;
      background: none;
      border: none;
      color: var(--text-dark);
      cursor: pointer;
    }
    @media (max-width: 768px) {
      .nav-links {
        display: none;
        position: fixed;
        top: 72px;
        left: 0;
        width: 100%;
        height: calc(100vh - 72px);
        background: white;
        flex-direction: column;
        justify-content: center;
        align-items: center;
        gap: 32px;
        z-index: 999;
        animation: fadeIn 0.3s ease;
      }
      .nav-links.active {
        display: flex;
      }
      .nav-links a {
        font-size: 20px;
      }
      .hamburger {
        display: block;
      }
      .btn-nav {
        padding: 12px 32px;
        font-size: 18px;
      }
    }
    @keyframes fadeIn {
      from { opacity: 0; transform: translateY(-10px); }
      to { opacity: 1; transform: translateY(0); }
    }
    /* 按钮系统 */
    .btn-primary {
      background: var(--primary);
      color: white;
      border: none;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 16px;
      display: inline-flex;
      align-items: center;
      gap: 8px;
      cursor: pointer;
      transition: all 0.2s ease;
      box-shadow: 0 2px 8px rgba(26,109,245,0.2);
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      transform: scale(1.02);
      box-shadow: 0 6px 16px rgba(26,109,245,0.3);
    }
    .btn-outline {
      background: transparent;
      color: var(--primary);
      border: 2px solid var(--primary);
      padding: 12px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      cursor: pointer;
      transition: all 0.2s;
    }
    .btn-outline:hover {
      background: var(--primary);
      color: white;
    }
    .btn-cta {
      background: var(--accent);
      color: white;
      border: none;
      padding: 16px 40px;
      border-radius: var(--radius-btn);
      font-weight: 700;
      font-size: 18px;
      cursor: pointer;
      transition: all 0.2s ease;
      box-shadow: 0 4px 14px rgba(255,107,53,0.25);
      display: inline-flex;
      align-items: center;
      gap: 10px;
    }
    .btn-cta:hover {
      background: var(--accent-dark);
      transform: scale(1.02);
    }
    /* 卡片 */
    .card {
      background: white;
      border-radius: var(--radius-md);
      padding: 32px;
      box-shadow: var(--card-shadow);
      transition: all 0.3s ease;
    }
    .card:hover {
      transform: translateY(-6px);
      box-shadow: var(--card-shadow-hover);
    }
    /* 数据数字 */
    .stat-number {
      font-size: 48px;
      font-weight: 800;
      color: var(--accent);
      line-height: 1.1;
    }
    /* FAQ 手风琴 */
    .faq-item {
      border-left: 4px solid var(--primary);
      background: #F1F5F9;
      margin-bottom: 16px;
      border-radius: 0 12px 12px 0;
      overflow: hidden;
      transition: all 0.3s;
    }
    .faq-question {
      padding: 20px 24px;
      font-weight: 700;
      font-size: 18px;
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      color: var(--text-dark);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease;
      background: white;
    }
    .faq-answer p {
      padding: 0 24px 20px;
      margin: 0;
      color: var(--text-muted);
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
    }
    /* 页脚 */
    .site-footer {
      background: #1E293B;
      color: #CBD5E1;
      padding: 64px 0 32px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 48px;
      margin-bottom: 48px;
    }
    @media (max-width: 768px) {
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }
    .footer-logo {
      font-size: 1.8rem;
      font-weight: 800;
      color: white;
    }
    .footer a {
      color: #94A3B8;
      transition: color 0.2s;
    }
    .footer a:hover {
      color: white;
    }