/* roulang page: index */
:root {
      --primary: #2D5CFF;
      --primary-hover: #1E4BD8;
      --accent: #FF6E30;
      --success: #00B578;
      --danger: #FA5151;
      --bg: #F5F6FA;
      --card-bg: #FFFFFF;
      --dark-bg: #1A2238;
      --text-body: #1F2329;
      --text-muted: #86909C;
      --text-on-dark: #FFFFFF;
      --text-on-dark-muted: #B0B8C1;
      --border-light: #E5E8EF;
      --radius-sm: 8px;
      --radius: 12px;
      --radius-lg: 16px;
      --shadow-sm: 0 2px 12px rgba(0,0,0,0.04);
      --shadow-md: 0 8px 24px rgba(0,0,0,0.06);
      --font-h1: 600 40px/1.3 "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
      --font-h2: 600 28px/1.4 "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
      --font-h3: 500 20px/1.5 "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
      --font-body: 400 16px/1.6 "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
      --font-small: 400 14px/1.5 "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
      --transition: all 200ms ease-out;
      --nav-height: 68px;
    }

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

    html {
      scroll-behavior: smooth;
      scroll-padding-top: var(--nav-height);
    }

    body {
      background-color: var(--bg);
      color: var(--text-body);
      font: var(--font-body);
      min-height: 100vh;
      display: flex;
      flex-direction: column;
    }

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

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

    button, .btn {
      font: var(--font-body);
      cursor: pointer;
      border: none;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      gap: 8px;
      transition: var(--transition);
      border-radius: var(--radius-sm);
      padding: 0 20px;
      height: 44px;
      font-weight: 500;
      white-space: nowrap;
    }

    .container {
      width: 100%;
      max-width: 1200px;
      margin-left: auto;
      margin-right: auto;
      padding-left: 24px;
      padding-right: 24px;
    }

    /* navigation */
    .site-header {
      position: sticky;
      top: 0;
      z-index: 1000;
      background-color: #FFFFFF;
      border-bottom: 1px solid var(--border-light);
      height: var(--nav-height);
      transition: box-shadow 0.25s ease;
    }

    .site-header.scrolled {
      box-shadow: 0 4px 16px rgba(0,0,0,0.04);
    }

    .nav-container {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 100%;
    }

    .logo {
      display: flex;
      align-items: center;
      gap: 10px;
      font-weight: 700;
      font-size: 22px;
      color: var(--primary);
      letter-spacing: 0.5px;
    }

    .logo-icon {
      font-size: 28px;
      color: var(--primary);
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 32px;
    }

    .nav-links a {
      font-size: 15px;
      font-weight: 500;
      color: var(--text-body);
      padding: 8px 0;
      border-bottom: 2px solid transparent;
      transition: var(--transition);
    }

    .nav-links a:hover,
    .nav-links a:focus-visible {
      color: var(--primary);
      border-bottom-color: var(--primary);
    }

    .nav-cta {
      background-color: var(--primary);
      color: white;
      padding: 8px 18px !important;
      border-radius: 30px !important;
      border-bottom: none !important;
      font-weight: 600;
    }

    .nav-cta:hover {
      background-color: var(--primary-hover) !important;
      color: white !important;
    }

    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      background: none;
      border: none;
      cursor: pointer;
      padding: 8px;
      z-index: 1001;
    }

    .hamburger span {
      display: block;
      width: 24px;
      height: 2.5px;
      background: var(--text-body);
      border-radius: 3px;
      transition: var(--transition);
    }

    .mobile-menu {
      position: fixed;
      top: 0;
      right: -100%;
      width: 75%;
      max-width: 320px;
      height: 100vh;
      background: #FFFFFF;
      box-shadow: -8px 0 30px rgba(0,0,0,0.08);
      display: flex;
      flex-direction: column;
      padding: 30px 24px;
      gap: 24px;
      transition: right 250ms ease-in-out;
      z-index: 999;
    }

    .mobile-menu.open {
      right: 0;
    }

    .mobile-menu a {
      font-size: 18px;
      font-weight: 500;
      padding: 12px 0;
      border-bottom: 1px solid var(--border-light);
    }

    /* hero */
    .hero {
      background: linear-gradient(135deg, #EFF2FA 0%, #F5F6FA 100%);
      padding: 60px 0 70px;
      border-bottom-left-radius: 40px;
      border-bottom-right-radius: 40px;
      margin-bottom: 0;
    }

    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 40px;
      align-items: center;
    }

    .hero-text h1 {
      font: var(--font-h1);
      color: #0B1424;
      margin-bottom: 20px;
    }

    .hero-text .sub {
      font-size: 17px;
      color: var(--text-muted);
      margin-bottom: 32px;
      max-width: 90%;
    }

    .hero-buttons {
      display: flex;
      flex-wrap: wrap;
      gap: 16px;
    }

    .btn-primary {
      background-color: var(--primary);
      color: white;
      box-shadow: 0 4px 12px rgba(45,92,255,0.3);
    }

    .btn-primary:hover {
      background-color: var(--primary-hover);
      box-shadow: 0 8px 18px rgba(45,92,255,0.35);
    }

    .btn-outline {
      background: transparent;
      border: 1.5px solid var(--primary);
      color: var(--primary);
    }

    .btn-outline:hover {
      background: rgba(45,92,255,0.06);
    }

    .hero-image img {
      border-radius: 28px;
      box-shadow: 0 20px 40px rgba(0,0,0,0.08);
      width: 100%;
    }

    /* sections common */
    .section {
      padding: 80px 0;
    }

    .section-title {
      text-align: center;
      margin-bottom: 16px;
    }

    .section-title h2 {
      font: var(--font-h2);
      color: #0B1424;
    }

    .section-sub {
      text-align: center;
      color: var(--text-muted);
      max-width: 640px;
      margin: 0 auto 50px;
      font-size: 16px;
    }

    /* service cards */
    .cards-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }

    .service-card {
      background: var(--card-bg);
      border-radius: var(--radius);
      padding: 28px 24px;
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
      display: flex;
      flex-direction: column;
      gap: 16px;
    }

    .service-card:hover {
      transform: translateY(-6px);
      box-shadow: var(--shadow-md);
    }

    .card-icon {
      font-size: 32px;
      color: var(--primary);
    }

    .service-card h3 {
      font: var(--font-h3);
    }

    .service-card p {
      color: var(--text-muted);
      font-size: 15px;
    }

    .tag-accent {
      color: var(--accent);
      font-weight: 600;
      font-size: 14px;
      display: flex;
      align-items: center;
      gap: 4px;
    }

    /* stats dark */
    .stats-section {
      background-color: var(--dark-bg);
      padding: 70px 0;
      color: white;
    }

    .stats-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 30px;
      text-align: center;
    }

    .stat-item .number {
      font-size: 42px;
      font-weight: 700;
      color: var(--accent);
    }

    .stat-item .label {
      color: var(--text-on-dark-muted);
      margin-top: 8px;
    }

    /* cases */
    .cases-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 24px;
    }

    .case-card {
      background: var(--card-bg);
      border-radius: var(--radius);
      display: flex;
      box-shadow: var(--shadow-sm);
      overflow: hidden;
    }

    .case-img {
      width: 160px;
      min-height: 140px;
      object-fit: cover;
    }

    .case-info {
      padding: 20px;
      display: flex;
      flex-direction: column;
      justify-content: center;
    }

    .case-info h3 {
      font: var(--font-h3);
      margin-bottom: 8px;
    }

    /* solution */
    .solution-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 28px;
    }

    .solution-item {
      background: var(--card-bg);
      border-radius: var(--radius);
      padding: 28px;
    }

    .solution-item i {
      color: var(--primary);
      font-size: 26px;
      margin-bottom: 16px;
    }

    .solution-item ul {
      list-style: none;
      margin-top: 12px;
    }

    .solution-item li {
      margin-bottom: 8px;
      color: var(--text-muted);
      font-size: 15px;
    }

    /* faq */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }

    .faq-item {
      border-bottom: 1px solid var(--border-light);
    }

    .faq-question {
      width: 100%;
      background: none;
      font: var(--font-h3);
      padding: 20px 0;
      display: flex;
      justify-content: space-between;
      cursor: pointer;
      color: var(--text-body);
    }

    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.3s ease, padding 0.3s ease;
      color: var(--text-muted);
    }

    .faq-item.active .faq-answer {
      max-height: 200px;
      padding-bottom: 16px;
    }

    /* cta */
    .cta-band {
      background-color: var(--primary);
      text-align: center;
      padding: 70px 24px;
      color: white;
      border-radius: 24px;
      margin: 20px 0;
    }

    .cta-band h2 {
      font-size: 32px;
      margin-bottom: 12px;
    }

    .btn-white {
      background: white;
      color: var(--primary);
      margin-top: 20px;
      font-weight: 600;
    }

    /* footer */
    .footer {
      background: var(--dark-bg);
      color: var(--text-on-dark-muted);
      padding: 60px 0 30px;
    }

    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1.5fr;
      gap: 30px;
    }

    .footer-logo {
      font-size: 20px;
      font-weight: 700;
      color: white;
      margin-bottom: 12px;
    }

    .footer a {
      color: var(--text-on-dark-muted);
    }

    .footer a:hover {
      color: white;
    }

    @media (max-width: 1023px) {
      .cards-grid, .solution-grid { grid-template-columns: repeat(2, 1fr); }
      .hero-grid { grid-template-columns: 1fr; }
      .hero-image { order: -1; max-width: 400px; margin: 0 auto; }
      .stats-grid { grid-template-columns: repeat(2, 1fr); }
      .footer-grid { grid-template-columns: repeat(2,1fr); }
    }

    @media (max-width: 767px) {
      .container { padding: 0 16px; }
      .nav-links { display: none; }
      .hamburger { display: flex; }
      .cards-grid, .solution-grid, .cases-grid, .stats-grid, .footer-grid {
        grid-template-columns: 1fr;
      }
      .case-card { flex-direction: column; }
      .case-img { width: 100%; height: 180px; }
      .hero { padding: 30px 0 50px; }
      h1 { font-size: 30px !important; }
    }