/* roulang page: index */
:root {
      --primary: #0EA5E9;
      --primary-dark: #0284C7;
      --accent: #F97316;
      --accent-dark: #EA580C;
      --bg: #F8FAFC;
      --card-bg: #FFFFFF;
      --dark-bg: #0F172A;
      --text-dark: #0F172A;
      --text-heading: #1E293B;
      --text-body: #475569;
      --text-muted: #64748B;
      --text-light: #94A3B8;
      --border-light: #E2E8F0;
      --shadow-sm: 0 1px 3px 0 rgba(0,0,0,0.04), 0 1px 2px -1px rgba(0,0,0,0.06);
      --shadow-card: 0 8px 20px -8px rgba(0,0,0,0.06);
      --shadow-hover: 0 12px 28px -6px rgba(0,0,0,0.1), 0 4px 12px -6px rgba(0,0,0,0.05);
      --radius-md: 12px;
      --radius-sm: 8px;
      --font-sans: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Helvetica Neue", sans-serif;
      --transition: all 0.25s ease;
    }

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

    body {
      font-family: var(--font-sans);
      background-color: var(--bg);
      color: var(--text-body);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }

    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 24px;
    }

    /* 导航 */
    .header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(12px);
      z-index: 50;
      height: 64px;
      display: flex;
      align-items: center;
      box-shadow: 0 1px 3px rgba(0,0,0,0.02);
      transition: var(--transition);
    }
    .header.scrolled {
      box-shadow: 0 4px 12px rgba(0,0,0,0.04);
    }
    .nav-bar {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .logo {
      font-weight: 700;
      font-size: 1.4rem;
      color: var(--text-dark);
      text-decoration: none;
      display: flex;
      align-items: center;
      gap: 6px;
      letter-spacing: -0.3px;
    }
    .logo i {
      color: var(--primary);
      font-size: 1.8rem;
    }
    .nav-links {
      display: flex;
      gap: 28px;
      align-items: center;
    }
    .nav-links a {
      text-decoration: none;
      color: var(--text-body);
      font-weight: 500;
      font-size: 0.95rem;
      transition: var(--transition);
      white-space: nowrap;
    }
    .nav-links a:hover {
      color: var(--primary);
    }
    .btn-primary-sm {
      background: var(--primary);
      color: white;
      padding: 10px 22px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      text-decoration: none;
      font-size: 0.9rem;
      transition: var(--transition);
      display: inline-block;
    }
    .btn-primary-sm:hover {
      background: var(--primary-dark);
      transform: translateY(-1px);
    }
    .hamburger {
      display: none;
      background: none;
      border: none;
      font-size: 1.6rem;
      color: var(--text-dark);
      cursor: pointer;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: 64px;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.98);
      backdrop-filter: blur(20px);
      flex-direction: column;
      align-items: center;
      padding: 32px 24px;
      gap: 24px;
      box-shadow: var(--shadow-sm);
      z-index: 45;
    }
    .mobile-menu a {
      font-size: 1.2rem;
      font-weight: 500;
      color: var(--text-dark);
      text-decoration: none;
    }
    .mobile-menu .btn-primary-sm {
      font-size: 1rem;
      padding: 12px 28px;
    }

    @media (max-width: 768px) {
      .nav-links { display: none; }
      .hamburger { display: block; }
      .mobile-menu.active { display: flex; }
    }

    /* 通用板块 */
    section {
      padding: 80px 0;
    }
    @media (max-width: 768px) {
      section { padding: 60px 0; }
    }
    .section-title {
      text-align: center;
      margin-bottom: 48px;
    }
    .section-title h2 {
      font-size: 2.25rem;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 12px;
    }
    .section-title p {
      color: var(--text-muted);
      font-size: 1.1rem;
    }

    /* Hero */
    .hero {
      padding: 120px 0 80px;
      background: radial-gradient(circle at 10% 20%, #F0F9FF 0%, #FFFFFF 80%);
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 48px;
    }
    .hero-text {
      flex: 1;
    }
    .hero-text h1 {
      font-size: 3rem;
      font-weight: 700;
      color: var(--text-dark);
      line-height: 1.2;
      margin-bottom: 20px;
    }
    .hero-text .sub {
      font-size: 1.2rem;
      color: #475569;
      margin-bottom: 32px;
      max-width: 480px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      text-decoration: none;
      transition: var(--transition);
    }
    .btn-primary:hover {
      background: var(--primary-dark);
      transform: translateY(-2px);
      box-shadow: 0 8px 18px rgba(14,165,233,0.3);
    }
    .btn-outline {
      background: transparent;
      border: 2px solid var(--primary);
      color: var(--primary);
      padding: 14px 32px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      text-decoration: none;
      transition: var(--transition);
    }
    .btn-outline:hover {
      background: var(--primary);
      color: white;
    }
    .hero-image {
      flex: 1;
      text-align: center;
    }
    .hero-image img {
      max-width: 100%;
      border-radius: 20px;
      box-shadow: 0 20px 35px -12px rgba(0,0,0,0.12);
    }
    @media (max-width: 768px) {
      .hero-grid { flex-direction: column; }
      .hero-text h1 { font-size: 2.2rem; }
      .hero-image { margin-top: 32px; }
    }

    /* 核心优势 四列 */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    .feature-card {
      background: var(--card-bg);
      padding: 32px 24px;
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      text-align: center;
    }
    .feature-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-hover);
      border: 1px solid var(--primary);
    }
    .feature-icon {
      font-size: 2.2rem;
      color: var(--primary);
      margin-bottom: 18px;
    }
    .feature-card h3 {
      font-size: 1.25rem;
      font-weight: 600;
      color: var(--text-heading);
      margin-bottom: 10px;
    }
    @media (max-width: 1024px) {
      .features-grid { grid-template-columns: repeat(2, 1fr); }
    }
    @media (max-width: 520px) {
      .features-grid { grid-template-columns: 1fr; }
    }

    /* 服务产品 交错 */
    .service-row {
      display: flex;
      align-items: center;
      gap: 48px;
      margin-bottom: 72px;
    }
    .service-row.reverse {
      flex-direction: row-reverse;
    }
    .service-content {
      flex: 1;
    }
    .service-content h3 {
      font-size: 1.8rem;
      font-weight: 700;
      color: var(--text-dark);
      margin-bottom: 16px;
    }
    .service-list {
      list-style: none;
      margin-top: 20px;
    }
    .service-list li {
      display: flex;
      align-items: center;
      gap: 10px;
      margin-bottom: 12px;
      color: var(--text-body);
    }
    .service-list i {
      color: var(--primary);
    }
    .service-img {
      flex: 1;
    }
    .service-img img {
      width: 100%;
      border-radius: 16px;
      box-shadow: var(--shadow-sm);
    }
    @media (max-width: 768px) {
      .service-row, .service-row.reverse {
        flex-direction: column;
      }
    }

    /* 数据背书 */
    .stats-bg {
      background: #F1F5F9;
    }
    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 32px;
      text-align: center;
    }
    .stat-number {
      font-size: 3rem;
      font-weight: 800;
      color: var(--accent);
      line-height: 1.1;
    }
    .stat-label {
      color: #64748B;
      font-size: 1rem;
      margin-top: 8px;
    }
    @media (max-width: 768px) {
      .stats-grid { grid-template-columns: repeat(2, 1fr); }
    }

    /* 流程 */
    .steps {
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap;
    }
    .step {
      display: flex;
      flex-direction: column;
      align-items: center;
      text-align: center;
      flex: 1;
    }
    .step-number {
      background: var(--primary);
      color: white;
      width: 48px;
      height: 48px;
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      font-weight: 700;
      font-size: 1.4rem;
      margin-bottom: 16px;
    }
    .step h4 {
      font-weight: 600;
      color: var(--text-dark);
    }
    .step-divider {
      width: 60px;
      height: 2px;
      background: #CBD5E1;
      margin: 0 8px;
    }
    @media (max-width: 768px) {
      .steps { flex-direction: column; gap: 28px; }
      .step-divider { display: none; }
    }

    /* FAQ */
    .faq-item {
      background: white;
      border-radius: var(--radius-md);
      margin-bottom: 16px;
      box-shadow: var(--shadow-sm);
      overflow: hidden;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      padding: 20px 24px;
      font-weight: 600;
      font-size: 1.1rem;
      cursor: pointer;
      background: white;
      border: none;
      width: 100%;
      text-align: left;
      color: var(--text-dark);
    }
    .faq-answer {
      padding: 0 24px 20px;
      color: #475569;
      display: none;
      line-height: 1.7;
    }
    .faq-item.active .faq-answer {
      display: block;
    }
    .faq-item.active .faq-question {
      border-left: 4px solid var(--primary);
    }

    /* CTA 深色区 */
    .cta-dark {
      background: var(--dark-bg);
      color: white;
      text-align: center;
      padding: 80px 24px;
      position: relative;
    }
    .cta-dark h2 {
      font-size: 2.2rem;
      font-weight: 700;
    }
    .btn-accent {
      background: var(--accent);
      color: white;
      padding: 18px 40px;
      border-radius: var(--radius-sm);
      font-weight: 700;
      text-decoration: none;
      display: inline-block;
      margin-top: 28px;
      transition: var(--transition);
    }
    .btn-accent:hover {
      background: var(--accent-dark);
      transform: scale(1.02);
    }

    /* 页脚 */
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
      padding: 48px 0;
    }
    .footer-brand p {
      margin-top: 12px;
      color: var(--text-muted);
    }
    .footer-links a {
      display: block;
      color: var(--text-body);
      text-decoration: none;
      margin-bottom: 10px;
    }
    .footer-copyright {
      background: #0F172A;
      color: #94A3B8;
      text-align: center;
      padding: 18px;
      font-size: 0.9rem;
    }
    @media (max-width: 768px) {
      .footer-grid { grid-template-columns: 1fr; }
    }