/* roulang page: index */
/* ----- 设计变量 ----- */
    :root {
      --primary: #1A5F7A;
      --primary-soft: #EFF6F9;
      --accent: #0D9488;
      --accent-dark: #0F766E;
      --bg: #F8FAFB;
      --surface: #FFFFFF;
      --text-main: #1E293B;
      --text-secondary: #475569;
      --text-muted: #64748B;
      --border: #E2E8F0;
      --success-light: #F0FDF9;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.04), 0 1px 2px rgba(0,0,0,0.06);
      --shadow-md: 0 10px 25px rgba(0,0,0,0.08), 0 4px 10px rgba(0,0,0,0.05);
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-lg: 16px;
      --font-sans: system-ui, -apple-system, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
      --transition: 200ms ease;
    }

    /* ----- 基础重置 ----- */
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    html {
      scroll-behavior: smooth;
      -webkit-font-smoothing: antialiased;
    }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg);
      color: var(--text-main);
      line-height: 1.8;
      font-size: 16px;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    a {
      text-decoration: none;
      color: inherit;
      transition: color var(--transition);
    }
    button, .btn {
      cursor: pointer;
      font-family: inherit;
    }
    .container {
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 20px;
    }
    @media (min-width: 768px) {
      .container {
        padding: 0 32px;
      }
    }

    /* ----- 导航 ----- */
    .site-header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(10px);
      -webkit-backdrop-filter: blur(10px);
      border-bottom: 1px solid var(--border);
      z-index: 50;
      transition: box-shadow var(--transition);
    }
    .header-shadow {
      box-shadow: 0 4px 12px rgba(0,0,0,0.05);
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 64px;
      max-width: 1200px;
      margin: 0 auto;
      padding: 0 20px;
    }
    .logo {
      display: flex;
      align-items: baseline;
      gap: 6px;
      font-weight: 700;
      font-size: 1.25rem;
      color: var(--primary);
      letter-spacing: -0.3px;
      white-space: nowrap;
    }
    .logo small {
      font-weight: 400;
      font-size: 0.75rem;
      color: var(--text-muted);
      margin-left: 4px;
    }
    .nav-links {
      display: none;
      align-items: center;
      gap: 28px;
    }
    .nav-links a {
      font-size: 0.95rem;
      font-weight: 500;
      color: var(--text-secondary);
      padding: 6px 0;
      border-bottom: 2px solid transparent;
      transition: color var(--transition), border-color var(--transition);
    }
    .nav-links a:hover {
      color: var(--primary);
      border-bottom-color: var(--accent);
    }
    .btn-primary-sm {
      background: var(--accent-dark);
      color: white;
      border: none;
      padding: 8px 20px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 0.9rem;
      transition: background var(--transition), transform var(--transition);
      display: inline-block;
    }
    .btn-primary-sm:hover {
      background: #0D6B63;
      transform: translateY(-1px);
    }
    .menu-toggle {
      display: flex;
      flex-direction: column;
      gap: 5px;
      background: transparent;
      border: none;
      width: 28px;
      height: 20px;
      justify-content: center;
    }
    .menu-toggle span {
      display: block;
      height: 2px;
      background: var(--text-main);
      border-radius: 2px;
    }
    #menu-checkbox {
      display: none;
    }
    .mobile-menu {
      display: none;
      background: white;
      border-top: 1px solid var(--border);
      padding: 16px 20px;
      flex-direction: column;
      gap: 16px;
    }
    #menu-checkbox:checked ~ .mobile-menu {
      display: flex;
    }
    .mobile-menu a {
      font-weight: 500;
      color: var(--text-secondary);
      font-size: 1rem;
    }
    @media (min-width: 769px) {
      .nav-links {
        display: flex;
      }
      .menu-toggle {
        display: none;
      }
      .mobile-menu {
        display: none !important;
      }
    }

    /* ----- 通用板块 ----- */
    .section {
      padding: 100px 0;
    }
    @media (max-width: 768px) {
      .section {
        padding: 64px 0;
      }
    }
    .section-title {
      font-size: 2rem;
      font-weight: 600;
      color: var(--text-main);
      margin-bottom: 16px;
      line-height: 1.3;
    }
    .section-subtitle {
      font-size: 1.125rem;
      color: var(--text-muted);
      margin-bottom: 48px;
    }
    @media (max-width: 640px) {
      .section-title {
        font-size: 1.75rem;
      }
    }

    /* ----- Hero ----- */
    .hero {
      min-height: 90vh;
      display: flex;
      align-items: center;
      background: linear-gradient(135deg, #F8FAFB 0%, #EFF6F9 100%);
      padding-top: 80px;
    }
    .hero-grid {
      display: flex;
      flex-direction: column;
      gap: 48px;
    }
    @media (min-width: 1024px) {
      .hero-grid {
        flex-direction: row;
        align-items: center;
        gap: 80px;
      }
      .hero-content {
        flex: 1;
      }
      .hero-image {
        flex: 1;
      }
    }
    .hero h1 {
      font-size: 2.5rem;
      font-weight: 700;
      color: #0F172A;
      line-height: 1.2;
      margin-bottom: 20px;
    }
    .hero p {
      font-size: 1.125rem;
      color: var(--text-muted);
      margin-bottom: 32px;
    }
    .hero-buttons {
      display: flex;
      flex-wrap: wrap;
      gap: 16px;
    }
    .btn-primary {
      background: var(--accent-dark);
      color: white;
      border: none;
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: 1rem;
      transition: background var(--transition), transform var(--transition);
    }
    .btn-primary:hover {
      background: #0D6B63;
      transform: translateY(-2px);
    }
    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
      padding: 14px 32px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      transition: background var(--transition);
    }
    .btn-outline:hover {
      background: #F0F9F9;
    }
    .hero-image img {
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-md);
      width: 100%;
      aspect-ratio: 4/3;
      object-fit: cover;
      background: #e2e8f0;
    }

    /* 痛点卡片 */
    .grid-3 {
      display: grid;
      grid-template-columns: 1fr;
      gap: 24px;
    }
    @media (min-width: 640px) {
      .grid-3 { grid-template-columns: repeat(2, 1fr); }
    }
    @media (min-width: 1024px) {
      .grid-3 { grid-template-columns: repeat(3, 1fr); }
    }
    .pain-card {
      background: var(--surface);
      padding: 28px 24px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-sm);
      transition: box-shadow var(--transition), transform var(--transition);
    }
    .pain-card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-4px);
    }
    .pain-icon {
      font-size: 2rem;
      margin-bottom: 16px;
      color: #b91c1c;
    }
    .pain-card h3 {
      font-size: 1.25rem;
      margin-bottom: 8px;
    }

    /* 解决方案图文交错 */
    .solution-row {
      display: flex;
      flex-direction: column;
      gap: 32px;
      margin-bottom: 80px;
    }
    @media (min-width: 768px) {
      .solution-row {
        flex-direction: row;
        align-items: center;
      }
      .solution-row.reverse {
        flex-direction: row-reverse;
      }
    }
    .solution-text {
      flex: 1;
    }
    .solution-img {
      flex: 1;
      border-radius: var(--radius-lg);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      background: #f1f5f9;
    }
    .solution-img img {
      width: 100%;
      height: 260px;
      object-fit: cover;
    }
    .feature-list {
      list-style: none;
      margin-top: 16px;
    }
    .feature-list li {
      display: flex;
      align-items: center;
      gap: 10px;
      margin-bottom: 10px;
      color: var(--text-secondary);
    }
    .feature-list li::before {
      content: "✓";
      color: var(--accent-dark);
      font-weight: 700;
    }

    /* 数据卡 */
    .stat-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 24px;
    }
    @media (min-width: 1024px) {
      .stat-grid { grid-template-columns: repeat(4, 1fr); }
    }
    .stat-card {
      background: var(--success-light);
      padding: 28px 20px;
      border-radius: var(--radius-card);
      text-align: center;
    }
    .stat-number {
      font-size: 2.2rem;
      font-weight: 700;
      color: var(--accent-dark);
    }

    /* 证言 */
    .testimonial-grid {
      display: grid;
      grid-template-columns: 1fr;
      gap: 24px;
    }
    @media (min-width: 768px) { .testimonial-grid { grid-template-columns: repeat(3, 1fr); } }
    .testimonial-card {
      background: var(--surface);
      padding: 32px;
      border-radius: var(--radius-lg);
      box-shadow: var(--shadow-sm);
    }
    .testimonial-text {
      font-style: italic;
      color: #334155;
      margin-bottom: 20px;
    }
    .avatar {
      width: 60px;
      height: 60px;
      background: #cbd5e1;
      border-radius: 50%;
      margin-bottom: 12px;
    }

    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    details {
      border-bottom: 1px solid var(--border);
      padding: 20px 0;
    }
    summary {
      font-weight: 600;
      font-size: 1.1rem;
      cursor: pointer;
      list-style: none;
      display: flex;
      justify-content: space-between;
      color: var(--text-main);
    }
    summary::after {
      content: "+";
      font-size: 1.5rem;
      color: var(--primary);
    }
    details[open] summary::after {
      content: "−";
    }
    .faq-answer {
      padding-top: 12px;
      color: var(--text-secondary);
    }

    /* CTA */
    .cta-block {
      background: var(--primary);
      color: white;
      text-align: center;
      padding: 100px 20px;
    }
    .cta-block h2 {
      color: white;
    }
    .cta-sub {
      color: rgba(255,255,255,0.85);
      margin-bottom: 32px;
    }
    .btn-white {
      background: white;
      color: var(--accent-dark);
      border: none;
      padding: 14px 38px;
      border-radius: var(--radius-btn);
      font-weight: 700;
      transition: background var(--transition);
    }
    .btn-white:hover {
      background: #F0FDF9;
    }

    /* 页脚 */
    .footer {
      background: #1E293B;
      color: #CBD5E1;
      padding: 60px 0 30px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 1fr;
      gap: 32px;
    }
    @media (min-width: 768px) {
      .footer-grid { grid-template-columns: 2fr 1fr 1fr 1fr; }
    }
    .footer a {
      color: #94a3b8;
    }
    .footer a:hover { color: white; }
    .copyright {
      border-top: 1px solid #334155;
      margin-top: 40px;
      padding-top: 20px;
      text-align: center;
      font-size: 0.9rem;
    }