/* roulang page: index */
/* ===== DESIGN TOKENS & RESET ===== */
    :root {
      --primary: #3B82C4;
      --primary-dark: #2B6CB0;
      --primary-light: #EFF6FF;
      --accent: #F5A623;
      --accent-dark: #D48B1A;
      --success: #10B981;
      --success-dark: #059669;
      --danger: #EF4444;
      --bg: #FAFBFD;
      --surface: #FFFFFF;
      --text-primary: #0F172A;
      --text-body: #475569;
      --text-muted: #94A3B8;
      --border: #E2E8F0;
      --border-light: #F1F5F9;
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 20px;
      --shadow-sm: 0 1px 3px rgba(0,0,0,0.06), 0 1px 2px rgba(0,0,0,0.04);
      --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
      --shadow-lg: 0 12px 28px rgba(0,0,0,0.10);
      --font-cn: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", sans-serif;
      --font-en: "Inter", system-ui, -apple-system, sans-serif;
      --max-width: 1280px;
      --nav-height: 64px;
    }

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

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: var(--font-cn);
      font-size: 16px;
      font-weight: 400;
      line-height: 1.7;
      color: var(--text-body);
      background-color: var(--bg);
      -webkit-font-smoothing: antialiased;
      -moz-osx-font-smoothing: grayscale;
    }

    a {
      text-decoration: none;
      color: inherit;
      transition: color 0.25s ease;
    }
    a:hover {
      color: var(--primary);
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    button, input {
      font-family: inherit;
    }
    ul {
      list-style: none;
    }

    /* Container */
    .container {
      max-width: var(--max-width);
      margin-left: auto;
      margin-right: auto;
      padding-left: 24px;
      padding-right: 24px;
    }

    /* Section spacing */
    section {
      padding-top: 80px;
      padding-bottom: 80px;
    }

    /* Headlines */
    h1, h2, h3, .h1, .h2, .h3 {
      font-weight: 700;
      color: var(--text-primary);
      letter-spacing: -0.01em;
    }
    h1, .h1 {
      font-size: 36px;
      line-height: 1.25;
    }
    h2, .h2 {
      font-size: 28px;
      line-height: 1.3;
    }
    h3, .h3 {
      font-size: 20px;
      font-weight: 600;
      line-height: 1.35;
    }

    /* Buttons */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      border-radius: var(--radius-sm);
      font-weight: 600;
      font-size: 16px;
      transition: all 0.25s ease;
      cursor: pointer;
      border: 2px solid transparent;
      white-space: nowrap;
      gap: 8px;
    }
    .btn-primary {
      background-color: var(--primary);
      color: white;
      box-shadow: 0 2px 8px rgba(59,130,196,0.3);
    }
    .btn-primary:hover {
      background-color: var(--primary-dark);
      box-shadow: 0 6px 16px rgba(59,130,196,0.35);
      color: white;
    }
    .btn-outline {
      background: transparent;
      border-color: var(--primary);
      color: var(--primary);
    }
    .btn-outline:hover {
      background-color: var(--primary-light);
      border-color: var(--primary-dark);
      color: var(--primary-dark);
    }
    .btn-success {
      background-color: var(--success);
      color: white;
      box-shadow: 0 2px 8px rgba(16,185,129,0.3);
    }
    .btn-success:hover {
      background-color: var(--success-dark);
      box-shadow: 0 6px 14px rgba(16,185,129,0.4);
      color: white;
    }
    .btn-lg {
      padding: 16px 40px;
      font-size: 18px;
      border-radius: var(--radius-md);
    }

    /* ===== NAVIGATION ===== */
    .header {
      position: sticky;
      top: 0;
      z-index: 1000;
      background: rgba(255,255,255,0.92);
      backdrop-filter: blur(16px);
      -webkit-backdrop-filter: blur(16px);
      border-bottom: 1px solid rgba(226,232,240,0.6);
      height: var(--nav-height);
      display: flex;
      align-items: center;
    }
    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      width: 100%;
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    .logo {
      font-size: 22px;
      font-weight: 700;
      color: var(--primary);
      letter-spacing: 0.02em;
      display: flex;
      align-items: center;
      gap: 6px;
    }
    .logo i {
      font-size: 24px;
    }
    .nav-links {
      display: flex;
      gap: 32px;
      align-items: center;
    }
    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-body);
      padding: 8px 0;
      border-bottom: 2px solid transparent;
      transition: all 0.2s;
    }
    .nav-links a:hover,
    .nav-links a.active {
      color: var(--primary);
      border-bottom-color: var(--primary);
    }
    .burger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      padding: 8px;
      background: none;
      border: none;
    }
    .burger span {
      width: 24px;
      height: 2px;
      background: var(--text-primary);
      border-radius: 2px;
      transition: all 0.3s;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: var(--nav-height);
      left: 0;
      width: 100%;
      height: calc(100vh - var(--nav-height));
      background: white;
      flex-direction: column;
      padding: 32px 24px;
      gap: 24px;
      z-index: 999;
      opacity: 0;
      transform: translateY(-8px);
      transition: opacity 0.3s, transform 0.3s;
    }
    .mobile-menu.open {
      display: flex;
      opacity: 1;
      transform: translateY(0);
    }
    .mobile-menu a {
      font-size: 18px;
      font-weight: 500;
      color: var(--text-primary);
      padding: 12px 0;
      border-bottom: 1px solid var(--border-light);
    }

    /* ===== HERO ===== */
    .hero {
      background: linear-gradient(135deg, #FFFFFF 0%, #F0F6FC 100%);
      padding-top: 40px;
      padding-bottom: 40px;
    }
    .hero-grid {
      display: flex;
      align-items: center;
      gap: 48px;
    }
    .hero-text {
      flex: 1 1 50%;
    }
    .hero-text h1 {
      margin-bottom: 16px;
    }
    .hero-subtitle {
      font-size: 18px;
      color: var(--text-body);
      margin-bottom: 32px;
      line-height: 1.6;
    }
    .hero-actions {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .hero-image {
      flex: 1 1 50%;
      border-radius: var(--radius-lg);
      overflow: hidden;
      box-shadow: var(--shadow-lg);
      background: white;
      transition: transform 0.3s;
    }
    .hero-image img {
      width: 100%;
      height: auto;
      border-radius: var(--radius-lg);
    }

    /* ===== FEATURES GRID ===== */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 48px;
    }
    .feature-item {
      text-align: center;
      background: var(--surface);
      border-radius: var(--radius-md);
      padding: 32px 24px;
      box-shadow: var(--shadow-sm);
      transition: all 0.25s ease;
    }
    .feature-item:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-2px);
    }
    .feature-icon {
      width: 56px;
      height: 56px;
      margin: 0 auto 20px;
      background: var(--primary-light);
      border-radius: 50%;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--primary);
      font-size: 26px;
    }
    .feature-item h3 {
      margin-bottom: 8px;
    }
    .feature-item p {
      font-size: 14px;
      color: var(--text-muted);
    }

    /* ===== PRODUCT CARDS ===== */
    .product-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 48px;
    }
    .product-card {
      background: var(--surface);
      border-radius: var(--radius-md);
      box-shadow: var(--shadow-sm);
      overflow: hidden;
      transition: all 0.25s ease;
      display: flex;
      flex-direction: column;
    }
    .product-card:hover {
      box-shadow: var(--shadow-md);
      transform: translateY(-2px);
    }
    .product-card img {
      width: 100%;
      aspect-ratio: 16 / 9;
      object-fit: cover;
      border-radius: var(--radius-md) var(--radius-md) 0 0;
    }
    .product-body {
      padding: 24px;
      display: flex;
      flex-direction: column;
      gap: 12px;
      flex: 1;
    }
    .product-body h3 {
      margin-bottom: 4px;
    }
    .product-desc {
      font-size: 14px;
      color: var(--text-muted);
      display: -webkit-box;
      -webkit-line-clamp: 2;
      -webkit-box-orient: vertical;
      overflow: hidden;
    }
    .product-tags {
      display: flex;
      flex-wrap: wrap;
      gap: 8px;
      margin: 8px 0;
    }
    .tag {
      background: var(--border-light);
      color: var(--text-body);
      padding: 4px 12px;
      border-radius: 20px;
      font-size: 12px;
      font-weight: 500;
    }
    .product-card .btn {
      margin-top: auto;
    }

    /* ===== CASES ===== */
    .cases-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 48px;
    }
    .case-card {
      position: relative;
      border-radius: var(--radius-md);
      overflow: hidden;
      aspect-ratio: 4 / 3;
      background: #0F172A;
    }
    .case-card img {
      width: 100%;
      height: 100%;
      object-fit: cover;
      transition: transform 0.4s ease;
    }
    .case-overlay {
      position: absolute;
      bottom: 0;
      left: 0;
      right: 0;
      background: linear-gradient(transparent, rgba(0,0,0,0.75));
      padding: 28px 20px 20px;
      color: white;
      transition: all 0.3s;
    }
    .case-card:hover img {
      transform: scale(1.04);
    }
    .case-card:hover .case-overlay {
      background: linear-gradient(transparent, rgba(0,0,0,0.85));
    }
    .case-overlay h3 {
      color: white;
      margin-bottom: 4px;
    }
    .case-tag {
      background: rgba(255,255,255,0.2);
      backdrop-filter: blur(4px);
      padding: 4px 12px;
      border-radius: 20px;
      font-size: 13px;
      font-weight: 500;
      display: inline-block;
      margin-bottom: 8px;
    }
    .case-desc {
      font-size: 14px;
      opacity: 0;
      max-height: 0;
      transition: all 0.3s;
      color: #CBD5E1;
    }
    .case-card:hover .case-desc {
      opacity: 1;
      max-height: 60px;
      margin-top: 8px;
    }

    /* ===== COMPARISON TABLE ===== */
    .comparison-wrapper {
      margin-top: 48px;
      overflow-x: auto;
    }
    .comp-table {
      width: 100%;
      border-collapse: collapse;
      background: white;
      border-radius: var(--radius-md);
      overflow: hidden;
      box-shadow: var(--shadow-sm);
      min-width: 600px;
    }
    .comp-table th {
      background: #F8FAFC;
      padding: 16px 24px;
      font-weight: 600;
      font-size: 18px;
      color: var(--text-primary);
      text-align: left;
      border-bottom: 1px solid var(--border);
    }
    .comp-table td {
      padding: 14px 24px;
      border-bottom: 1px solid var(--border-light);
      color: var(--text-body);
    }
    .comp-table tr:last-child td {
      border-bottom: none;
    }
    .comp-table .highlight-col {
      background: #F0F6FC;
      color: var(--primary);
      font-weight: 600;
    }
    .fa-check-circle {
      color: var(--success);
    }
    .fa-times-circle {
      color: #CBD5E1;
    }

    /* ===== FAQ ===== */
    .faq-list {
      max-width: 720px;
      margin: 48px auto 0;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      margin-bottom: 8px;
    }
    .faq-question {
      width: 100%;
      text-align: left;
      background: none;
      border: none;
      padding: 20px 16px;
      font-size: 18px;
      font-weight: 600;
      color: var(--text-primary);
      display: flex;
      justify-content: space-between;
      align-items: center;
      cursor: pointer;
      transition: background 0.2s;
      border-radius: var(--radius-sm);
    }
    .faq-question:hover {
      background: #F8FAFC;
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      padding: 0 16px;
      background: #F8FAFC;
      border-radius: 0 0 var(--radius-sm) var(--radius-sm);
      color: var(--text-body);
      font-size: 15px;
    }
    .faq-item.active .faq-answer {
      max-height: 200px;
      padding: 16px;
    }
    .faq-question i {
      transition: transform 0.3s;
      color: var(--text-muted);
    }
    .faq-item.active .faq-question i {
      transform: rotate(45deg);
      color: var(--primary);
    }

    /* ===== CTA BANNER ===== */
    .cta-banner {
      background: #EFF6FF;
      text-align: center;
      padding: 64px 24px;
      border-radius: var(--radius-lg);
      margin: 0 24px;
    }
    .cta-banner h2 {
      margin-bottom: 12px;
    }
    .cta-banner p {
      margin-bottom: 32px;
      color: var(--text-body);
      font-size: 17px;
    }

    /* ===== FOOTER ===== */
    .footer {
      background: #0F172A;
      color: #CBD5E1;
      padding: 60px 0 30px;
      margin-top: 80px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 32px;
    }
    .footer-col h4 {
      color: white;
      margin-bottom: 16px;
      font-size: 16px;
      font-weight: 600;
    }
    .footer-col a {
      display: block;
      color: #CBD5E1;
      margin-bottom: 10px;
      font-size: 14px;
    }
    .footer-col a:hover {
      color: var(--primary);
    }
    .social-icons {
      display: flex;
      gap: 14px;
      margin-top: 12px;
    }
    .social-icons a {
      color: #CBD5E1;
      font-size: 20px;
      transition: color 0.2s;
    }
    .social-icons a:hover {
      color: var(--primary);
    }
    .footer-bottom {
      border-top: 1px solid #1E293B;
      margin-top: 40px;
      padding-top: 24px;
      text-align: center;
      font-size: 13px;
      color: #64748B;
    }

    /* ===== RESPONSIVE ===== */
    @media (max-width: 1024px) {
      .product-grid,
      .cases-grid,
      .features-grid {
        grid-template-columns: repeat(2, 1fr);
      }
      .footer-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 768px) {
      section {
        padding-top: 56px;
        padding-bottom: 56px;
      }
      h1, .h1 { font-size: 28px; }
      h2, .h2 { font-size: 24px; }
      .nav-links { display: none; }
      .burger { display: flex; }
      .hero-grid {
        flex-direction: column;
        text-align: center;
      }
      .hero-actions {
        justify-content: center;
      }
      .features-grid,
      .product-grid,
      .cases-grid {
        grid-template-columns: 1fr;
      }
      .footer-grid {
        grid-template-columns: 1fr;
      }
      .container {
        padding-left: 16px;
        padding-right: 16px;
      }
      .cta-banner {
        margin: 0 16px;
      }
    }
    @media (max-width: 520px) {
      .hero-actions {
        flex-direction: column;
        align-items: center;
      }
    }