/* roulang page: index */
:root {
      --primary: #4E6EF2;
      --primary-hover: #3A5CE4;
      --primary-ghost: rgba(78, 110, 242, 0.04);
      --success: #00B578;
      --warning: #FF9F0A;
      --error: #FA5151;
      --bg: #F5F6FA;
      --card-bg: #FFFFFF;
      --dark-bg: #1F2329;
      --text-primary: #1F2329;
      --text-secondary: #86909C;
      --text-muted: #C9CDD4;
      --border-light: #E5E8EF;
      --radius-card: 12px;
      --radius-btn: 8px;
      --radius-input: 8px;
      --shadow-card: 0 2px 12px rgba(0, 0, 0, 0.04);
      --shadow-card-hover: 0 4px 16px rgba(0, 0, 0, 0.08);
      --font-h1: 36px;
      --font-h2: 28px;
      --font-h3: 20px;
      --font-body: 16px;
      --font-small: 14px;
      --font-metric: 32px;
      --space-section: 80px;
      --space-mobile-section: 48px;
      --max-width: 1200px;
      --header-height: 64px;
    }
    * {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
    }
    body {
      font-family: system-ui, -apple-system, 'Segoe UI', Roboto, 'Helvetica Neue', 'PingFang SC', 'Microsoft YaHei', sans-serif;
      background-color: var(--bg);
      color: var(--text-primary);
      line-height: 1.6;
      font-size: var(--font-body);
      -webkit-font-smoothing: antialiased;
    }
    a {
      color: inherit;
      text-decoration: none;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    button, input {
      font-family: inherit;
    }
    .container {
      max-width: var(--max-width);
      margin: 0 auto;
      padding: 0 24px;
    }
    @media (max-width: 768px) {
      .container {
        padding: 0 16px;
      }
    }

    /* Header & Navigation */
    #header {
      position: fixed;
      top: 0;
      left: 0;
      width: 100%;
      height: var(--header-height);
      background: var(--card-bg);
      display: flex;
      align-items: center;
      z-index: 100;
      box-shadow: 0 1px 0 rgba(0,0,0,0.02);
      transition: box-shadow 0.2s ease;
    }
    #header.scroll-shadow {
      box-shadow: 0 2px 12px rgba(0,0,0,0.06);
    }
    .header-inner {
      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: 20px;
      font-weight: 700;
      color: var(--text-primary);
      letter-spacing: -0.3px;
    }
    .logo span {
      color: var(--primary);
    }
    .nav-menu {
      display: flex;
      gap: 32px;
      list-style: none;
      font-size: var(--font-small);
      font-weight: 500;
      color: var(--text-secondary);
    }
    .nav-menu a {
      transition: color 0.2s;
      padding: 0 4px;
    }
    .nav-menu a:hover, .nav-menu a.active {
      color: var(--primary);
    }
    .btn-primary {
      background: var(--primary);
      color: white;
      border: none;
      padding: 10px 20px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: var(--font-small);
      cursor: pointer;
      transition: background 0.2s, transform 0.1s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
    }
    .btn-primary:hover {
      background: var(--primary-hover);
      transform: translateY(-1px);
    }
    .btn-outline {
      background: transparent;
      border: 1px solid var(--primary);
      color: var(--primary);
      padding: 10px 20px;
      border-radius: var(--radius-btn);
      font-weight: 600;
      font-size: var(--font-small);
      cursor: pointer;
      transition: background 0.2s, transform 0.1s;
      display: inline-flex;
      align-items: center;
      justify-content: center;
    }
    .btn-outline:hover {
      background: var(--primary-ghost);
      transform: translateY(-1px);
    }
    .btn-primary:disabled, .btn-outline:disabled {
      background: #F0F1F5;
      border-color: #F0F1F5;
      color: var(--text-muted);
      cursor: not-allowed;
      transform: none;
    }

    /* Mobile Nav */
    .hamburger {
      display: none;
      flex-direction: column;
      gap: 5px;
      cursor: pointer;
      background: none;
      border: none;
    }
    .hamburger span {
      width: 24px;
      height: 2px;
      background: var(--text-primary);
      border-radius: 2px;
    }
    .mobile-menu {
      display: none;
      position: fixed;
      top: var(--header-height);
      left: 0;
      width: 100%;
      background: var(--card-bg);
      flex-direction: column;
      padding: 24px;
      box-shadow: 0 8px 20px rgba(0,0,0,0.08);
      z-index: 99;
    }
    .mobile-menu a {
      display: block;
      padding: 14px 0;
      font-size: 18px;
      font-weight: 500;
      border-bottom: 1px solid var(--border-light);
      color: var(--text-primary);
    }
    .mobile-menu .btn-primary {
      margin-top: 16px;
      width: 100%;
    }
    @media (max-width: 767px) {
      .nav-menu, .header-inner .btn-primary {
        display: none;
      }
      .hamburger {
        display: flex;
      }
      .mobile-menu.show {
        display: flex;
      }
    }

    /* Sections */
    section {
      padding: var(--space-section) 0;
    }
    @media (max-width: 768px) {
      section {
        padding: var(--space-mobile-section) 0;
      }
    }
    .section-title {
      font-size: var(--font-h2);
      font-weight: 600;
      line-height: 1.4;
      margin-bottom: 12px;
      color: var(--text-primary);
    }
    .section-subtitle {
      font-size: var(--font-body);
      color: var(--text-secondary);
      margin-bottom: 40px;
      max-width: 600px;
    }

    /* Hero */
    #hero {
      padding-top: calc(var(--header-height) + 60px);
      background: var(--bg);
      position: relative;
      overflow: hidden;
      background-image: url('/assets/images/backpic/back-1.webp');
      background-size: cover;
      background-position: center;
      background-blend-mode: overlay;
      background-color: rgba(245, 246, 250, 0.7);
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }
    @media (max-width: 768px) {
      .hero-grid {
        grid-template-columns: 1fr;
        gap: 32px;
      }
    }
    .hero-content h1 {
      font-size: var(--font-h1);
      font-weight: 700;
      line-height: 1.3;
      color: var(--text-primary);
      margin-bottom: 16px;
    }
    .hero-content .subtitle {
      font-size: 18px;
      color: var(--text-secondary);
      margin-bottom: 24px;
    }
    .hero-buttons {
      display: flex;
      gap: 16px;
      flex-wrap: wrap;
    }
    .metrics-row {
      display: flex;
      gap: 24px;
      margin-top: 40px;
    }
    .metric-card {
      background: var(--card-bg);
      padding: 16px 20px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      text-align: center;
      min-width: 110px;
    }
    .metric-number {
      font-size: var(--font-metric);
      font-weight: 700;
      color: var(--primary);
      line-height: 1.2;
    }
    .metric-label {
      font-size: var(--font-small);
      color: var(--text-secondary);
    }

    /* Features */
    .features-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .feature-card {
      background: var(--card-bg);
      padding: 24px;
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      transition: box-shadow 0.2s;
    }
    .feature-card:hover {
      box-shadow: var(--shadow-card-hover);
    }
    .feature-icon {
      width: 40px;
      height: 40px;
      background: #F0F1F5;
      border-radius: var(--radius-btn);
      display: flex;
      align-items: center;
      justify-content: center;
      margin-bottom: 16px;
      color: var(--primary);
      font-size: 20px;
    }
    .feature-card h3 {
      font-size: var(--font-h3);
      font-weight: 500;
      margin-bottom: 8px;
    }
    .feature-card p {
      font-size: var(--font-small);
      color: var(--text-secondary);
      line-height: 1.5;
    }
    @media (max-width: 1023px) {
      .features-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 767px) {
      .features-grid {
        grid-template-columns: 1fr;
      }
    }

    /* Insights */
    #insights {
      background: #F0F2F5;
      border-radius: 24px;
      margin: 0 24px;
      max-width: var(--max-width);
      margin-left: auto;
      margin-right: auto;
      padding: 48px 24px;
    }
    .insights-row {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      text-align: center;
      gap: 24px;
    }
    .insight-item .big-number {
      font-size: var(--font-metric);
      font-weight: 700;
      color: var(--text-primary);
    }
    .insight-item .unit {
      font-size: var(--font-small);
      color: var(--text-secondary);
    }
    @media (max-width: 767px) {
      .insights-row {
        grid-template-columns: 1fr 1fr;
      }
    }

    /* Solutions */
    .solutions-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
    }
    .solution-card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      overflow: hidden;
      box-shadow: var(--shadow-card);
      transition: 0.2s;
    }
    .solution-card:hover {
      box-shadow: var(--shadow-card-hover);
    }
    .solution-img {
      width: 100%;
      aspect-ratio: 16/9;
      background: #F0F1F5;
      display: flex;
      align-items: center;
      justify-content: center;
      overflow: hidden;
    }
    .solution-img img {
      object-fit: cover;
      width: 100%;
      height: 100%;
    }
    .solution-body {
      padding: 20px;
    }
    .solution-body h3 {
      font-size: var(--font-h3);
      font-weight: 500;
      margin-bottom: 8px;
    }
    .solution-body p {
      font-size: var(--font-small);
      color: var(--text-secondary);
      margin-bottom: 12px;
    }
    .text-link {
      color: var(--primary);
      font-weight: 500;
      font-size: var(--font-small);
      display: inline-flex;
      align-items: center;
      gap: 4px;
    }
    @media (max-width: 1023px) {
      .solutions-grid {
        grid-template-columns: repeat(2, 1fr);
      }
    }
    @media (max-width: 767px) {
      .solutions-grid {
        grid-template-columns: 1fr;
      }
    }

    /* Cases */
    .cases-scroll {
      display: flex;
      gap: 24px;
      overflow-x: auto;
      padding-bottom: 16px;
      scrollbar-width: thin;
    }
    .case-card {
      background: var(--card-bg);
      border-radius: var(--radius-card);
      box-shadow: var(--shadow-card);
      padding: 20px;
      min-width: 280px;
      border-left: 4px solid var(--primary);
      display: flex;
      flex-direction: column;
      gap: 12px;
    }
    .case-brand {
      font-weight: 600;
      font-size: 18px;
    }
    .compare-bar {
      display: flex;
      align-items: center;
      gap: 8px;
      font-size: var(--font-small);
    }
    .bar {
      height: 8px;
      background: #E5E8EF;
      border-radius: 4px;
      flex: 1;
    }
    .bar-fill {
      height: 8px;
      border-radius: 4px;
      background: var(--success);
    }
    .case-quote {
      color: var(--text-secondary);
      font-style: italic;
    }
    @media (max-width: 767px) {
      .cases-scroll {
        flex-direction: column;
        overflow-x: visible;
      }
      .case-card {
        min-width: auto;
      }
    }

    /* FAQ */
    .faq-list {
      max-width: 800px;
      margin: 0 auto;
    }
    .faq-item {
      border-bottom: 1px solid var(--border-light);
      padding: 16px 0;
    }
    .faq-question {
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-weight: 500;
      font-size: var(--font-body);
      cursor: pointer;
      background: none;
      border: none;
      width: 100%;
      text-align: left;
      color: var(--text-primary);
    }
    .faq-answer {
      max-height: 0;
      overflow: hidden;
      transition: max-height 0.25s ease;
      font-size: var(--font-small);
      color: var(--text-secondary);
      padding-top: 0;
    }
    .faq-item.open .faq-answer {
      max-height: 200px;
      padding-top: 12px;
    }
    .faq-icon {
      font-size: 20px;
      color: var(--text-secondary);
    }

    /* CTA */
    .cta-card {
      background: var(--card-bg);
      border-radius: 24px;
      padding: 48px;
      text-align: center;
      box-shadow: var(--shadow-card);
    }
    .cta-form {
      display: flex;
      gap: 16px;
      margin-top: 24px;
      justify-content: center;
      flex-wrap: wrap;
    }
    .input-group {
      flex: 1;
      min-width: 180px;
    }
    .input-group input {
      width: 100%;
      padding: 12px 16px;
      border: 1px solid var(--border-light);
      border-radius: var(--radius-input);
      font-size: var(--font-body);
      background: white;
      transition: 0.2s;
    }
    .input-group input:focus {
      outline: none;
      border-color: var(--primary);
      box-shadow: 0 0 0 3px rgba(78,110,242,0.15);
    }
    .privacy-note {
      font-size: var(--font-small);
      color: var(--text-muted);
      margin-top: 16px;
    }

    /* Footer */
    #footer {
      background: var(--dark-bg);
      color: var(--text-muted);
      padding: 48px 0 24px;
      font-size: var(--font-small);
    }
    .footer-grid {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 32px;
    }
    .footer-col h4 {
      color: white;
      margin-bottom: 16px;
      font-weight: 600;
    }
    .footer-col a {
      display: block;
      color: var(--text-muted);
      margin-bottom: 8px;
      transition: color 0.15s;
    }
    .footer-col a:hover {
      color: white;
    }
    .copyright {
      margin-top: 40px;
      border-top: 1px solid rgba(255,255,255,0.1);
      padding-top: 20px;
      text-align: center;
    }
    @media (max-width: 767px) {
      .footer-grid {
        grid-template-columns: 1fr 1fr;
      }
    }