/* roulang page: index */
:root {
      --primary: #1D4ED8;
      --primary-hover: #1E40AF;
      --accent: #0EA5E9;
      --amber: #F59E0B;
      --bg-main: #F8FAFC;
      --bg-white: #FFFFFF;
      --bg-dark: #0B132B;
      --text-main: #0F172A;
      --text-body: #334155;
      --text-muted: #64748B;
      --border-color: #E2E8F0;
      --radius-sm: 8px;
      --radius-md: 12px;
      --radius-lg: 16px;
      --shadow-sm: 0 1px 3px rgba(15, 23, 42, 0.06);
      --shadow-card: 0 4px 6px -1px rgba(15, 23, 42, 0.05), 0 10px 15px -3px rgba(15, 23, 42, 0.08);
      --shadow-hover: 0 20px 25px -5px rgba(15, 23, 42, 0.1), 0 10px 10px -5px rgba(15, 23, 42, 0.04);
      --transition: all 0.3s cubic-bezier(0.16, 1, 0.3, 1);
    }
    *, *::before, *::after {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    html {
      scroll-behavior: smooth;
      font-size: 16px;
    }
    body {
      font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
      background-color: var(--bg-main);
      color: var(--text-body);
      line-height: 1.75;
      letter-spacing: -0.01em;
      -webkit-font-smoothing: antialiased;
    }
    a {
      color: inherit;
      text-decoration: none;
      transition: var(--transition);
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    .container {
      width: 100%;
      max-width: 1280px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 24px;
      padding-right: 24px;
    }
    .section-padding {
      padding-top: 88px;
      padding-bottom: 88px;
    }
    .section-padding-sm {
      padding-top: 60px;
      padding-bottom: 60px;
    }
    .top-bar {
      background-color: #EFF6FF;
      height: 38px;
      border-bottom: 1px solid #DBEAFE;
      font-size: 0.82rem;
      color: #1E40AF;
      display: flex;
      align-items: center;
    }
    .top-bar-inner {
      display: flex;
      justify-content: space-between;
      align-items: center;
      width: 100%;
    }
    .header-nav {
      position: sticky;
      top: 0;
      z-index: 999;
      background: rgba(255, 255, 255, 0.96);
      backdrop-filter: blur(10px);
      border-bottom: 1px solid var(--border-color);
      box-shadow: var(--shadow-sm);
    }
    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .brand-logo {
      display: flex;
      align-items: center;
      gap: 10px;
      font-size: 1.25rem;
      font-weight: 700;
      color: var(--text-main);
    }
    .brand-icon {
      width: 36px;
      height: 36px;
      background: linear-gradient(135deg, var(--primary), var(--accent));
      border-radius: var(--radius-sm);
      display: flex;
      align-items: center;
      justify-content: center;
      color: #fff;
      font-weight: 900;
      font-size: 1.1rem;
    }
    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
      list-style: none;
    }
    .nav-links a {
      font-size: 0.95rem;
      font-weight: 500;
      color: var(--text-body);
    }
    .nav-links a:hover, .nav-links a.active {
      color: var(--primary);
    }
    .btn {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 10px 24px;
      font-size: 0.95rem;
      font-weight: 600;
      border-radius: var(--radius-sm);
      cursor: pointer;
      border: 1px solid transparent;
      transition: var(--transition);
      white-space: nowrap;
    }
    .btn-primary {
      background-color: var(--primary);
      color: #ffffff;
      box-shadow: 0 4px 12px rgba(29, 78, 216, 0.25);
    }
    .btn-primary:hover {
      background-color: var(--primary-hover);
      transform: translateY(-2px);
      box-shadow: 0 6px 16px rgba(29, 78, 216, 0.35);
    }
    .btn-outline {
      border-color: var(--border-color);
      background-color: #ffffff;
      color: var(--text-main);
    }
    .btn-outline:hover {
      border-color: var(--primary);
      color: var(--primary);
      background-color: #F8FAFC;
    }
    .section-head {
      text-align: center;
      max-width: 800px;
      margin: 0 auto 56px auto;
    }
    .section-tag {
      display: inline-block;
      padding: 4px 14px;
      background-color: #DBEAFE;
      color: var(--primary);
      font-size: 0.8rem;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.05em;
      border-radius: 999px;
      margin-bottom: 12px;
    }
    .section-title {
      font-size: clamp(1.6rem, 2.8vw, 2.3rem);
      font-weight: 800;
      color: var(--text-main);
      line-height: 1.3;
      margin-bottom: 16px;
    }
    .section-desc {
      font-size: 1.05rem;
      color: var(--text-muted);
      line-height: 1.8;
    }
    /* Hero */
    .hero-section {
      background: radial-gradient(circle at 80% 20%, rgba(219, 234, 254, 0.6) 0%, rgba(248, 250, 252, 0) 60%), #ffffff;
      padding: 60px 0 90px 0;
      border-bottom: 1px solid var(--border-color);
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1.15fr 0.85fr;
      gap: 48px;
      align-items: center;
    }
    .hero-h1 {
      font-size: clamp(2.1rem, 3.8vw, 3.2rem);
      line-height: 1.22;
      font-weight: 800;
      color: var(--text-main);
      margin-bottom: 24px;
    }
    .hero-p {
      font-size: 1.12rem;
      color: var(--text-body);
      line-height: 1.85;
      margin-bottom: 32px;
    }
    .hero-actions {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
      margin-bottom: 32px;
    }
    .hero-preview {
      position: relative;
      border-radius: var(--radius-lg);
      overflow: hidden;
      box-shadow: var(--shadow-hover);
      border: 1px solid rgba(226, 232, 240, 0.8);
      background: #ffffff;
    }
    .hero-preview img {
      width: 100%;
      height: 380px;
      object-fit: cover;
    }
    .hero-preview-badge {
      position: absolute;
      bottom: 16px;
      left: 16px;
      right: 16px;
      background: rgba(15, 23, 42, 0.85);
      backdrop-filter: blur(8px);
      padding: 12px 18px;
      border-radius: var(--radius-sm);
      color: #ffffff;
      font-size: 0.85rem;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    /* Grid cards */
    .grid-4 {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
    }
    .grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 30px;
    }
    .grid-2 {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 36px;
    }
    .card-box {
      background-color: #ffffff;
      border-radius: var(--radius-md);
      padding: 32px 28px;
      border: 1px solid var(--border-color);
      box-shadow: var(--shadow-card);
      transition: var(--transition);
      display: flex;
      flex-direction: column;
      position: relative;
    }
    .card-box:hover {
      transform: translateY(-4px);
      box-shadow: var(--shadow-hover);
      border-color: #CBD5E1;
    }
    .card-icon {
      width: 48px;
      height: 48px;
      border-radius: var(--radius-sm);
      background-color: #EFF6FF;
      color: var(--primary);
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 1.4rem;
      font-weight: 700;
      margin-bottom: 20px;
    }
    .card-title {
      font-size: 1.2rem;
      font-weight: 700;
      color: var(--text-main);
      margin-bottom: 12px;
    }
    .card-desc {
      font-size: 0.95rem;
      color: var(--text-muted);
      line-height: 1.7;
    }
    /* Timeline / Steps */
    .timeline-steps {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
      position: relative;
    }
    .timeline-item {
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 28px 24px;
      position: relative;
      box-shadow: var(--shadow-sm);
    }
    .step-number {
      font-size: 2.2rem;
      font-weight: 900;
      color: #DBEAFE;
      line-height: 1;
      margin-bottom: 12px;
    }
    /* Dark Section */
    .dark-section {
      background-color: var(--bg-dark);
      color: #ffffff;
      background-image: radial-gradient(circle at 10% 20%, rgba(29, 78, 216, 0.25) 0%, transparent 40%),
                        radial-gradient(circle at 90% 80%, rgba(14, 165, 233, 0.2) 0%, transparent 40%);
    }
    .dark-section .section-title {
      color: #ffffff;
    }
    .dark-section .section-desc {
      color: #94A3B8;
    }
    .dark-card {
      background: rgba(255, 255, 255, 0.05);
      border: 1px solid rgba(255, 255, 255, 0.12);
      border-radius: var(--radius-md);
      padding: 32px;
      backdrop-filter: blur(12px);
    }
    /* Metrics */
    .metrics-bar {
      background: #ffffff;
      border-radius: var(--radius-lg);
      border: 1px solid var(--border-color);
      padding: 40px 32px;
      box-shadow: var(--shadow-card);
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 24px;
      text-align: center;
    }
    .metric-value {
      font-size: 2.8rem;
      font-weight: 800;
      color: var(--primary);
      line-height: 1.1;
      margin-bottom: 8px;
    }
    .metric-label {
      font-size: 1rem;
      font-weight: 600;
      color: var(--text-main);
      margin-bottom: 4px;
    }
    .metric-sub {
      font-size: 0.85rem;
      color: var(--text-muted);
    }
    /* Accordion FAQ */
    .faq-container {
      max-width: 860px;
      margin: 0 auto;
      display: flex;
      flex-direction: column;
      gap: 16px;
    }
    details.faq-item {
      background: #ffffff;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 20px 24px;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }
    details.faq-item[open] {
      border-color: #BFDBFE;
      box-shadow: var(--shadow-card);
    }
    summary.faq-q {
      font-size: 1.05rem;
      font-weight: 700;
      color: var(--text-main);
      cursor: pointer;
      list-style: none;
      display: flex;
      justify-content: space-between;
      align-items: center;
    }
    summary.faq-q::-webkit-details-marker {
      display: none;
    }
    summary.faq-q::after {
      content: '+';
      font-size: 1.4rem;
      color: var(--primary);
      font-weight: 400;
      transition: transform 0.2s ease;
    }
    details[open] summary.faq-q::after {
      transform: rotate(45deg);
    }
    .faq-a {
      margin-top: 14px;
      padding-top: 14px;
      border-top: 1px solid #F1F5F9;
      font-size: 0.95rem;
      color: var(--text-body);
      line-height: 1.8;
    }
    /* Contact CTA */
    .cta-card-wrapper {
      background: linear-gradient(135deg, #EFF6FF 0%, #DBEAFE 100%);
      border: 1px solid #BFDBFE;
      border-radius: var(--radius-lg);
      padding: 56px 48px;
    }
    .cta-grid {
      display: grid;
      grid-template-columns: 1.1fr 0.9fr;
      gap: 48px;
      align-items: center;
    }
    .form-group {
      margin-bottom: 16px;
    }
    .form-label {
      display: block;
      font-size: 0.88rem;
      font-weight: 600;
      color: var(--text-main);
      margin-bottom: 6px;
    }
    .form-control {
      width: 100%;
      padding: 12px 16px;
      border-radius: var(--radius-sm);
      border: 1px solid var(--border-color);
      background-color: #ffffff;
      font-size: 0.95rem;
      color: var(--text-main);
      outline: none;
      transition: var(--transition);
    }
    .form-control:focus {
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(29, 78, 216, 0.15);
    }
    /* Footer */
    footer.site-footer {
      background-color: #0F172A;
      color: #94A3B8;
      padding: 72px 0 36px 0;
      font-size: 0.92rem;
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 1.6fr 1fr 1fr 1.2fr;
      gap: 40px;
      margin-bottom: 56px;
    }
    .footer-title {
      font-size: 1rem;
      font-weight: 700;
      color: #ffffff;
      margin-bottom: 20px;
    }
    .footer-links {
      list-style: none;
      display: flex;
      flex-direction: column;
      gap: 12px;
    }
    .footer-links a:hover {
      color: #ffffff;
    }
    .footer-bottom {
      border-top: 1px solid #1E293B;
      padding-top: 32px;
      display: flex;
      justify-content: space-between;
      align-items: center;
      flex-wrap: wrap;
      gap: 16px;
      font-size: 0.85rem;
    }
    /* Responsive Breakpoints */
    @media (max-width: 1024px) {
      .grid-4, .timeline-steps, .metrics-bar {
        grid-template-columns: repeat(2, 1fr);
      }
      .grid-3 {
        grid-template-columns: repeat(2, 1fr);
      }
      .hero-grid, .cta-grid {
        grid-template-columns: 1fr;
      }
      .footer-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 768px) {
      .top-bar {
        display: none;
      }
      .header-inner {
        height: 64px;
      }
      .nav-links {
        display: none;
      }
      .section-padding {
        padding-top: 60px;
        padding-bottom: 60px;
      }
      .grid-3, .grid-2 {
        grid-template-columns: 1fr;
      }
      .cta-card-wrapper {
        padding: 32px 20px;
      }
      .footer-grid {
        grid-template-columns: 1fr;
      }
    }
    @media (max-width: 520px) {
      .grid-4, .timeline-steps, .metrics-bar {
        grid-template-columns: 1fr;
      }
      .btn {
        width: 100%;
      }
      .hero-actions {
        flex-direction: column;
      }
    }