/* roulang page: index */
:root {
      --primary: #00E599;
      --primary-dark: #0FD68C;
      --secondary: #00A389;
      --accent: #FF6B35;
      --bg-dark: #0D1117;
      --bg-surface: #161B22;
      --bg-card: #21262D;
      --text-main: #FFFFFF;
      --text-muted: #C9D1D9;
      --text-dim: #8B949E;
      --border-color: rgba(0, 229, 153, 0.15);
      --border-light: rgba(255, 255, 255, 0.08);
      --shadow-card: 0 8px 24px rgba(0, 0, 0, 0.35);
      --radius-sm: 6px;
      --radius-md: 12px;
      --radius-lg: 18px;
      --transition: all 0.25s cubic-bezier(0.4, 0, 0.2, 1);
    }

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

    html {
      scroll-behavior: smooth;
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", "PingFang SC", "Microsoft YaHei", sans-serif;
      background-color: var(--bg-dark);
      color: var(--text-main);
      line-height: 1.6;
    }

    body {
      background-color: var(--bg-dark);
      overflow-x: hidden;
    }

    a {
      color: inherit;
      text-decoration: none;
      transition: var(--transition);
    }

    ul, ol {
      list-style: none;
    }

    img {
      max-width: 100%;
      height: auto;
      display: block;
    }

    .container {
      width: 100%;
      max-width: 1280px;
      margin: 0 auto;
      padding: 0 24px;
    }

    /* Top Bar */
    .top-bar {
      background: #090d12;
      border-bottom: 1px solid var(--border-light);
      font-size: 13px;
      color: var(--text-dim);
      padding: 8px 0;
    }
    .top-bar-inner {
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    .top-info span {
      margin-right: 20px;
    }
    .top-badge {
      background: rgba(0, 229, 153, 0.1);
      color: var(--primary);
      padding: 2px 8px;
      border-radius: var(--radius-sm);
      border: 1px solid rgba(0, 229, 153, 0.2);
    }

    /* Header Nav */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 100;
      background: rgba(22, 27, 34, 0.92);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-color);
    }
    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .brand-logo {
      display: flex;
      align-items: center;
      gap: 12px;
      font-size: 20px;
      font-weight: 700;
      color: var(--text-main);
      letter-spacing: 0.5px;
    }
    .logo-icon {
      width: 32px;
      height: 32px;
      background: linear-gradient(135deg, var(--primary), var(--secondary));
      border-radius: 8px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: #000;
      font-weight: 900;
      font-size: 18px;
    }
    .nav-menu {
      display: flex;
      align-items: center;
      gap: 32px;
    }
    .nav-item {
      font-size: 15px;
      color: var(--text-muted);
      font-weight: 500;
    }
    .nav-item:hover, .nav-item.active {
      color: var(--primary);
    }
    .header-actions {
      display: flex;
      align-items: center;
      gap: 16px;
    }
    .nav-toggle {
      display: none;
      background: none;
      border: none;
      color: var(--text-main);
      font-size: 24px;
      cursor: pointer;
    }

    /* Buttons */
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      font-size: 15px;
      font-weight: 600;
      border-radius: var(--radius-sm);
      cursor: pointer;
      transition: var(--transition);
      border: 1px solid transparent;
      min-height: 44px;
    }
    .btn-primary {
      background: var(--primary);
      color: #061e14;
      box-shadow: 0 4px 16px rgba(0, 229, 153, 0.3);
    }
    .btn-primary:hover {
      background: #1affab;
      transform: translateY(-2px);
      box-shadow: 0 6px 20px rgba(0, 229, 153, 0.45);
    }
    .btn-secondary {
      background: var(--bg-card);
      color: var(--text-main);
      border: 1px solid var(--border-color);
    }
    .btn-secondary:hover {
      border-color: var(--primary);
      color: var(--primary);
      transform: translateY(-2px);
    }
    .btn-accent {
      background: var(--accent);
      color: #fff;
      box-shadow: 0 4px 16px rgba(255, 107, 53, 0.3);
    }
    .btn-accent:hover {
      background: #ff7d4d;
      transform: translateY(-2px);
    }

    /* Section Global */
    .section {
      padding: 90px 0;
      position: relative;
    }
    .section-alt {
      background-color: var(--bg-surface);
      border-top: 1px solid var(--border-light);
      border-bottom: 1px solid var(--border-light);
    }
    .section-header {
      text-align: center;
      max-width: 800px;
      margin: 0 auto 56px;
    }
    .section-tag {
      display: inline-block;
      font-size: 13px;
      font-weight: 700;
      color: var(--primary);
      text-transform: uppercase;
      letter-spacing: 1.5px;
      margin-bottom: 12px;
      background: rgba(0, 229, 153, 0.1);
      padding: 4px 14px;
      border-radius: 20px;
      border: 1px solid rgba(0, 229, 153, 0.2);
    }
    .section-title {
      font-size: 34px;
      font-weight: 700;
      margin-bottom: 16px;
      color: var(--text-main);
      line-height: 1.3;
    }
    .section-desc {
      font-size: 16px;
      color: var(--text-muted);
      line-height: 1.7;
    }

    /* 1. Hero Section */
    .hero-section {
      padding: 100px 0 80px;
      background: radial-gradient(circle at 50% 20%, rgba(0, 229, 153, 0.12) 0%, transparent 65%),
                  linear-gradient(180deg, #090d12 0%, var(--bg-dark) 100%);
      position: relative;
      overflow: hidden;
      border-bottom: 1px solid var(--border-light);
    }
    .hero-content {
      text-align: center;
      max-width: 960px;
      margin: 0 auto;
    }
    .hero-burst {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      background: rgba(255, 107, 53, 0.15);
      border: 1px solid rgba(255, 107, 53, 0.4);
      color: #ff9166;
      font-size: 13px;
      font-weight: 600;
      padding: 6px 16px;
      border-radius: 30px;
      margin-bottom: 24px;
    }
    .hero-title {
      font-size: 48px;
      font-weight: 800;
      line-height: 1.25;
      margin-bottom: 24px;
      letter-spacing: -0.5px;
    }
    .hero-title span {
      background: linear-gradient(120deg, #ffffff 30%, var(--primary) 100%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }
    .hero-desc {
      font-size: 18px;
      color: var(--text-muted);
      max-width: 820px;
      margin: 0 auto 36px;
      line-height: 1.8;
    }
    .hero-cta-group {
      display: flex;
      justify-content: center;
      gap: 16px;
      margin-bottom: 48px;
    }
    .hero-preview {
      margin-top: 30px;
      background: var(--bg-card);
      border-radius: var(--radius-lg);
      border: 1px solid var(--border-color);
      box-shadow: 0 20px 50px rgba(0, 0, 0, 0.6);
      overflow: hidden;
      position: relative;
    }
    .hero-preview img {
      width: 100%;
      height: 480px;
      object-fit: cover;
      filter: contrast(105%) brightness(95%);
    }
    .hero-overlay-tag {
      position: absolute;
      bottom: 24px;
      left: 24px;
      background: rgba(13, 17, 23, 0.85);
      backdrop-filter: blur(8px);
      padding: 12px 20px;
      border-radius: var(--radius-md);
      border: 1px solid var(--border-color);
      font-size: 14px;
      color: var(--primary);
    }

    /* 2. Metrics Section */
    .metrics-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    .metric-card {
      background: var(--bg-card);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 32px 24px;
      text-align: center;
      transition: var(--transition);
      box-shadow: var(--shadow-card);
    }
    .metric-card:hover {
      border-color: var(--primary);
      transform: translateY(-4px);
    }
    .metric-value {
      font-size: 40px;
      font-weight: 800;
      color: var(--primary);
      margin-bottom: 8px;
      line-height: 1;
    }
    .metric-label {
      font-size: 16px;
      font-weight: 600;
      color: var(--text-main);
      margin-bottom: 8px;
    }
    .metric-sub {
      font-size: 13px;
      color: var(--text-dim);
    }

    /* 3. Product Intro */
    .product-intro-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }
    .product-visual {
      background: var(--bg-card);
      border-radius: var(--radius-lg);
      border: 1px solid var(--border-color);
      overflow: hidden;
      box-shadow: var(--shadow-card);
    }
    .product-visual img {
      width: 100%;
      height: 380px;
      object-fit: cover;
    }
    .product-detail-item {
      margin-bottom: 24px;
    }
    .product-detail-item h4 {
      font-size: 18px;
      color: var(--primary);
      margin-bottom: 8px;
      display: flex;
      align-items: center;
      gap: 8px;
    }
    .product-detail-item p {
      font-size: 15px;
      color: var(--text-muted);
      line-height: 1.7;
    }

    /* 4. Core Advantages (6 cards) */
    .advantages-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .adv-card {
      background: var(--bg-card);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 32px 24px;
      transition: var(--transition);
      position: relative;
    }
    .adv-card:hover {
      border-color: var(--primary);
      transform: translateY(-4px);
    }
    .adv-icon {
      width: 44px;
      height: 44px;
      background: rgba(0, 229, 153, 0.1);
      border-radius: 10px;
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--primary);
      font-weight: bold;
      margin-bottom: 20px;
    }
    .adv-card h3 {
      font-size: 19px;
      color: var(--text-main);
      margin-bottom: 12px;
    }
    .adv-card p {
      font-size: 14px;
      color: var(--text-muted);
      line-height: 1.7;
    }

    /* 5. Product Matrix (3 cards) */
    .pricing-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }
    .price-card {
      background: var(--bg-card);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-lg);
      padding: 40px 30px;
      display: flex;
      flex-direction: column;
      position: relative;
      transition: var(--transition);
    }
    .price-card.featured {
      border-color: var(--primary);
      background: linear-gradient(180deg, rgba(0, 229, 153, 0.08) 0%, var(--bg-card) 40%);
      transform: scale(1.03);
    }
    .price-badge {
      position: absolute;
      top: -12px;
      left: 50%;
      transform: translateX(-50%);
      background: var(--primary);
      color: #000;
      font-size: 12px;
      font-weight: 700;
      padding: 4px 14px;
      border-radius: 20px;
    }
    .price-name {
      font-size: 22px;
      font-weight: 700;
      margin-bottom: 12px;
    }
    .price-target {
      font-size: 14px;
      color: var(--text-dim);
      margin-bottom: 24px;
      min-height: 40px;
    }
    .price-feature-list {
      margin-bottom: 36px;
      flex-grow: 1;
    }
    .price-feature-item {
      display: flex;
      align-items: flex-start;
      gap: 10px;
      font-size: 14px;
      color: var(--text-muted);
      margin-bottom: 14px;
    }
    .price-feature-item::before {
      content: "✓";
      color: var(--primary);
      font-weight: bold;
    }

    /* 6. Dark Tech Showcase */
    .dark-tech-box {
      background: linear-gradient(135deg, #111720 0%, #0d121a 100%);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-lg);
      padding: 50px;
      display: grid;
      grid-template-columns: 1.2fr 0.8fr;
      gap: 40px;
      align-items: center;
    }
    .tech-list-box {
      display: grid;
      gap: 20px;
    }
    .tech-point {
      background: rgba(255, 255, 255, 0.03);
      border: 1px solid var(--border-light);
      padding: 20px;
      border-radius: var(--radius-md);
    }
    .tech-point h4 {
      color: var(--primary);
      font-size: 16px;
      margin-bottom: 6px;
    }
    .tech-point p {
      color: var(--text-muted);
      font-size: 14px;
    }
    .tech-media img {
      border-radius: var(--radius-md);
      border: 1px solid var(--border-light);
    }

    /* 7. Case & Comparison */
    .comparison-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 30px;
    }
    .comp-col {
      background: var(--bg-card);
      border-radius: var(--radius-lg);
      padding: 36px;
      border: 1px solid var(--border-light);
    }
    .comp-col.highlight {
      border-color: var(--primary);
      background: rgba(0, 229, 153, 0.03);
    }
    .comp-title {
      font-size: 20px;
      font-weight: 700;
      margin-bottom: 24px;
      display: flex;
      align-items: center;
      gap: 10px;
    }
    .comp-list li {
      margin-bottom: 18px;
      font-size: 14px;
      color: var(--text-muted);
      line-height: 1.6;
      display: flex;
      gap: 10px;
    }

    /* 8. User Stories */
    .stories-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .story-card {
      background: var(--bg-card);
      border-radius: var(--radius-md);
      border: 1px solid var(--border-light);
      overflow: hidden;
      transition: var(--transition);
    }
    .story-card:hover {
      border-color: var(--primary);
      transform: translateY(-4px);
    }
    .story-card img {
      height: 200px;
      width: 100%;
      object-fit: cover;
    }
    .story-body {
      padding: 24px;
    }
    .story-badge {
      font-size: 12px;
      color: var(--primary);
      margin-bottom: 8px;
      font-weight: 600;
    }
    .story-body h3 {
      font-size: 17px;
      margin-bottom: 10px;
      color: var(--text-main);
    }
    .story-body p {
      font-size: 14px;
      color: var(--text-muted);
      line-height: 1.6;
    }

    /* 9. Milestones */
    .timeline-wrap {
      position: relative;
      max-width: 900px;
      margin: 0 auto;
    }
    .timeline-wrap::before {
      content: "";
      position: absolute;
      top: 0;
      bottom: 0;
      left: 50%;
      width: 2px;
      background: var(--border-color);
      transform: translateX(-50%);
    }
    .timeline-node {
      position: relative;
      margin-bottom: 40px;
      width: 50%;
    }
    .timeline-node:nth-child(odd) {
      left: 0;
      padding-right: 40px;
      text-align: right;
    }
    .timeline-node:nth-child(even) {
      left: 50%;
      padding-left: 40px;
      text-align: left;
    }
    .node-dot {
      position: absolute;
      top: 6px;
      width: 14px;
      height: 14px;
      background: var(--primary);
      border-radius: 50%;
      box-shadow: 0 0 10px var(--primary);
    }
    .timeline-node:nth-child(odd) .node-dot {
      right: -7px;
    }
    .timeline-node:nth-child(even) .node-dot {
      left: -7px;
    }
    .node-content {
      background: var(--bg-card);
      padding: 20px;
      border-radius: var(--radius-md);
      border: 1px solid var(--border-light);
    }
    .node-title {
      font-size: 16px;
      font-weight: 700;
      color: var(--primary);
      margin-bottom: 6px;
    }
    .node-desc {
      font-size: 13px;
      color: var(--text-muted);
    }

    /* 10. Tech Insights */
    .insights-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .insight-card {
      background: var(--bg-card);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 28px;
      display: flex;
      flex-direction: column;
    }
    .insight-date {
      font-size: 12px;
      color: var(--text-dim);
      margin-bottom: 8px;
    }
    .insight-card h3 {
      font-size: 17px;
      color: var(--text-main);
      margin-bottom: 12px;
      line-height: 1.5;
    }
    .insight-card p {
      font-size: 14px;
      color: var(--text-muted);
      line-height: 1.6;
      flex-grow: 1;
    }

    /* 11. Security & Reliability */
    .security-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 20px;
    }
    .sec-item {
      background: var(--bg-card);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      padding: 24px;
      text-align: center;
    }
    .sec-item h4 {
      font-size: 16px;
      color: var(--primary);
      margin-bottom: 8px;
    }
    .sec-item p {
      font-size: 13px;
      color: var(--text-dim);
      line-height: 1.6;
    }

    /* 12. FAQ Accordion */
    .faq-container {
      max-width: 860px;
      margin: 0 auto;
    }
    .faq-item {
      background: var(--bg-card);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-md);
      margin-bottom: 16px;
      overflow: hidden;
    }
    .faq-item summary {
      padding: 20px 24px;
      font-size: 16px;
      font-weight: 600;
      color: var(--text-main);
      cursor: pointer;
      display: flex;
      justify-content: space-between;
      align-items: center;
      user-select: none;
    }
    .faq-item summary::-webkit-details-marker {
      display: none;
    }
    .faq-item summary::after {
      content: "+";
      font-size: 20px;
      color: var(--primary);
    }
    .faq-item[open] summary::after {
      content: "−";
    }
    .faq-answer {
      padding: 0 24px 20px;
      font-size: 14px;
      color: var(--text-muted);
      line-height: 1.7;
    }

    /* 13. Final CTA Form */
    .cta-wrapper {
      background: linear-gradient(135deg, rgba(0, 229, 153, 0.1) 0%, rgba(22, 27, 34, 0.9) 100%);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-lg);
      padding: 60px 40px;
      display: grid;
      grid-template-columns: 1fr 1.2fr;
      gap: 48px;
      align-items: center;
    }
    .cta-info h2 {
      font-size: 32px;
      margin-bottom: 16px;
      line-height: 1.3;
    }
    .cta-info p {
      font-size: 15px;
      color: var(--text-muted);
      line-height: 1.7;
    }
    .lead-form {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 16px;
    }
    .form-group {
      display: flex;
      flex-direction: column;
      gap: 6px;
    }
    .form-group.full {
      grid-column: span 2;
    }
    .form-group label {
      font-size: 13px;
      color: var(--text-dim);
    }
    .form-control {
      background: var(--bg-dark);
      border: 1px solid var(--border-light);
      border-radius: var(--radius-sm);
      padding: 12px 16px;
      color: #fff;
      font-size: 14px;
      outline: none;
      transition: var(--transition);
    }
    .form-control:focus {
      border-color: var(--primary);
      box-shadow: 0 0 0 2px rgba(0, 229, 153, 0.2);
    }

    /* Footer */
    .site-footer {
      background: #090d12;
      border-top: 1px solid var(--border-light);
      padding: 70px 0 30px;
      color: var(--text-dim);
      font-size: 14px;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1.5fr;
      gap: 40px;
      margin-bottom: 50px;
    }
    .footer-col h4 {
      color: var(--text-main);
      font-size: 15px;
      margin-bottom: 20px;
      font-weight: 600;
    }
    .footer-col ul li {
      margin-bottom: 12px;
    }
    .footer-col ul li a:hover {
      color: var(--primary);
    }
    .footer-bottom {
      border-top: 1px solid rgba(255, 255, 255, 0.05);
      padding-top: 30px;
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 13px;
    }

    /* Responsive */
    @media (max-width: 1024px) {
      .metrics-grid, .advantages-grid, .pricing-grid, .stories-grid, .insights-grid, .security-grid {
        grid-template-columns: repeat(2, 1fr);
      }
      .product-intro-grid, .dark-tech-box, .comparison-grid, .cta-wrapper {
        grid-template-columns: 1fr;
      }
      .price-card.featured {
        transform: none;
      }
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }

    @media (max-width: 767px) {
      .top-bar {
        display: none;
      }
      .section {
        padding: 56px 0;
      }
      .hero-title {
        font-size: 32px;
      }
      .hero-desc {
        font-size: 15px;
      }
      .hero-cta-group {
        flex-direction: column;
      }
      .nav-menu {
        display: none;
        position: absolute;
        top: 72px;
        left: 0;
        right: 0;
        background: var(--bg-surface);
        flex-direction: column;
        padding: 24px;
        border-bottom: 1px solid var(--border-color);
        gap: 16px;
      }
      .nav-menu.active {
        display: flex;
      }
      .nav-toggle {
        display: block;
      }
      .metrics-grid, .advantages-grid, .pricing-grid, .stories-grid, .insights-grid, .security-grid {
        grid-template-columns: 1fr;
      }
      .timeline-wrap::before {
        left: 10px;
      }
      .timeline-node {
        width: 100%;
        padding-left: 36px !important;
        padding-right: 0 !important;
        text-align: left !important;
      }
      .timeline-node .node-dot {
        left: 3px !important;
      }
      .lead-form {
        grid-template-columns: 1fr;
      }
      .form-group.full {
        grid-column: span 1;
      }
      .footer-grid {
        grid-template-columns: 1fr;
      }
      .footer-bottom {
        flex-direction: column;
        gap: 12px;
        text-align: center;
      }
    }