/* roulang page: index */
:root {
      --bg-white: #FFFFFF;
      --bg-light: #F8FAFC;
      --bg-card: #FFFFFF;
      --bg-dark: #0B0F19;
      --bg-dark-card: #131A29;
      --text-main: #0F172A;
      --text-muted: #64748B;
      --text-light: #94A3B8;
      --primary: #0B0F19;
      --accent-cyan: #00E599;
      --accent-indigo: #6366F1;
      --border-color: #E2E8F0;
      --border-dark: rgba(255, 255, 255, 0.1);
      --radius-sm: 6px;
      --radius-md: 10px;
      --radius-lg: 16px;
      --shadow-sm: 0 2px 8px rgba(0, 0, 0, 0.04);
      --shadow-md: 0 8px 24px -4px rgba(0, 0, 0, 0.06);
      --shadow-lg: 0 16px 36px -6px rgba(0, 0, 0, 0.1);
      --transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
    }

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

    html {
      scroll-behavior: smooth;
    }

    body {
      font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
      background-color: var(--bg-white);
      color: var(--text-main);
      line-height: 1.75;
      font-size: 15px;
      -webkit-font-smoothing: antialiased;
      overflow-x: hidden;
    }

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

    a:hover, a:focus {
      color: var(--accent-indigo);
      text-decoration: none;
    }

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

    /* Top Utility Bar */
    .top-bar-custom {
      background-color: #F1F5F9;
      border-bottom: 1px solid var(--border-color);
      font-size: 13px;
      color: var(--text-muted);
      padding: 8px 0;
    }

    .top-bar-inner {
      display: flex;
      justify-content: space-between;
      align-items: center;
    }

    .tech-badge {
      display: inline-flex;
      align-items: center;
      gap: 6px;
    }

    .tech-badge span {
      display: inline-block;
      width: 6px;
      height: 6px;
      border-radius: 50%;
      background: var(--accent-cyan);
    }

    /* Main Sticky Nav */
    .main-nav-wrapper {
      position: sticky;
      top: 0;
      z-index: 1000;
      background: rgba(255, 255, 255, 0.94);
      backdrop-filter: blur(12px);
      border-bottom: 1px solid var(--border-color);
      transition: var(--transition);
    }

    .nav-container {
      display: flex;
      justify-content: space-between;
      align-items: center;
      height: 72px;
    }

    .nav-logo {
      display: flex;
      align-items: center;
      gap: 10px;
      font-size: 20px;
      font-weight: 700;
      letter-spacing: -0.02em;
      color: var(--bg-dark);
    }

    .nav-logo-icon {
      width: 32px;
      height: 32px;
      background: var(--bg-dark);
      border-radius: var(--radius-sm);
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--accent-cyan);
      font-weight: 800;
      font-size: 16px;
    }

    .nav-links {
      display: flex;
      list-style: none;
      margin: 0;
      gap: 28px;
    }

    .nav-links li a {
      font-size: 14px;
      font-weight: 500;
      color: var(--text-muted);
      position: relative;
      padding: 6px 0;
    }

    .nav-links li a:hover,
    .nav-links li a.active {
      color: var(--bg-dark);
    }

    .nav-links li a.active::after,
    .nav-links li a:hover::after {
      content: '';
      position: absolute;
      bottom: 0;
      left: 0;
      width: 100%;
      height: 2px;
      background-color: var(--accent-indigo);
      border-radius: 2px;
    }

    .nav-cta {
      display: inline-flex;
      align-items: center;
      padding: 8px 18px;
      font-size: 13px;
      font-weight: 600;
      border: 1px solid var(--border-color);
      border-radius: var(--radius-sm);
      background: var(--bg-white);
      color: var(--bg-dark);
      box-shadow: var(--shadow-sm);
      transition: var(--transition);
    }

    .nav-cta:hover {
      border-color: var(--bg-dark);
      background: var(--bg-dark);
      color: #fff;
    }

    /* Section Layout Standard */
    section {
      padding: 90px 0;
      position: relative;
    }

    .section-light {
      background-color: var(--bg-white);
    }

    .section-gray {
      background-color: var(--bg-light);
    }

    .section-dark {
      background-color: var(--bg-dark);
      color: #FFFFFF;
    }

    .section-header {
      margin-bottom: 50px;
    }

    .section-tag {
      display: inline-block;
      font-size: 12px;
      font-weight: 700;
      text-transform: uppercase;
      letter-spacing: 0.08em;
      color: var(--accent-indigo);
      margin-bottom: 8px;
    }

    .section-dark .section-tag {
      color: var(--accent-cyan);
    }

    .section-title {
      font-size: 32px;
      font-weight: 800;
      letter-spacing: -0.02em;
      line-height: 1.25;
      margin-bottom: 14px;
      color: var(--text-main);
    }

    .section-dark .section-title {
      color: #FFFFFF;
    }

    .section-desc {
      font-size: 15px;
      color: var(--text-muted);
      max-width: 720px;
      line-height: 1.7;
    }

    .section-dark .section-desc {
      color: var(--text-light);
    }

    /* Hero Section */
    .hero-section {
      padding: 100px 0 80px;
      background: linear-gradient(180deg, #FFFFFF 0%, #F8FAFC 100%);
      border-bottom: 1px solid var(--border-color);
    }

    .hero-h1 {
      font-size: 46px;
      font-weight: 800;
      letter-spacing: -0.03em;
      line-height: 1.15;
      color: var(--bg-dark);
      margin-bottom: 20px;
    }

    .hero-h1 span {
      background: linear-gradient(120deg, #0B0F19 0%, #6366F1 100%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
    }

    .hero-desc {
      font-size: 16px;
      color: var(--text-muted);
      line-height: 1.8;
      margin-bottom: 30px;
      max-width: 580px;
    }

    .hero-btn-group {
      display: flex;
      flex-wrap: wrap;
      gap: 14px;
      margin-bottom: 32px;
    }

    .btn-primary-custom {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 28px;
      font-size: 14px;
      font-weight: 600;
      background: var(--bg-dark);
      color: #FFFFFF;
      border-radius: var(--radius-sm);
      box-shadow: 0 4px 12px rgba(11, 15, 25, 0.15);
      border: 1px solid transparent;
      transition: var(--transition);
    }

    .btn-primary-custom:hover {
      background: #1E293B;
      color: #fff;
      transform: translateY(-2px);
    }

    .btn-secondary-custom {
      display: inline-flex;
      align-items: center;
      justify-content: center;
      padding: 12px 26px;
      font-size: 14px;
      font-weight: 600;
      background: var(--bg-white);
      color: var(--text-main);
      border-radius: var(--radius-sm);
      border: 1px solid var(--border-color);
      transition: var(--transition);
    }

    .btn-secondary-custom:hover {
      border-color: var(--text-main);
      transform: translateY(-2px);
    }

    .hero-visual-card {
      background: var(--bg-white);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-lg);
      padding: 12px;
      box-shadow: var(--shadow-md);
      position: relative;
    }

    .hero-visual-img {
      border-radius: var(--radius-md);
      overflow: hidden;
      max-height: 400px;
      object-fit: cover;
      width: 100%;
    }

    /* Common Card Styles */
    .feature-card {
      background: var(--bg-white);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 30px;
      height: 100%;
      transition: var(--transition);
    }

    .feature-card:hover {
      border-color: #CBD5E1;
      transform: translateY(-4px);
      box-shadow: var(--shadow-md);
    }

    .card-icon {
      width: 44px;
      height: 44px;
      background: #F1F5F9;
      border-radius: var(--radius-sm);
      display: flex;
      align-items: center;
      justify-content: center;
      font-size: 18px;
      font-weight: 700;
      color: var(--bg-dark);
      margin-bottom: 20px;
    }

    .card-title {
      font-size: 18px;
      font-weight: 700;
      margin-bottom: 10px;
      color: var(--text-main);
    }

    .card-desc {
      font-size: 14px;
      color: var(--text-muted);
      line-height: 1.65;
    }

    .card-meta {
      display: inline-block;
      margin-top: 14px;
      font-size: 12px;
      font-weight: 600;
      color: var(--accent-indigo);
    }

    /* Wide Solution Card */
    .solution-card {
      background: var(--bg-white);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-lg);
      padding: 36px;
      margin-bottom: 24px;
      transition: var(--transition);
    }

    .solution-card:hover {
      border-color: var(--accent-indigo);
      box-shadow: var(--shadow-md);
    }

    .pill-tag {
      background: #EEF2FF;
      color: var(--accent-indigo);
      padding: 4px 10px;
      border-radius: 20px;
      font-size: 12px;
      font-weight: 600;
    }

    .checklist {
      list-style: none;
      margin: 18px 0 0;
    }

    .checklist li {
      font-size: 14px;
      color: var(--text-muted);
      margin-bottom: 8px;
      position: relative;
      padding-left: 20px;
    }

    .checklist li::before {
      content: '✓';
      position: absolute;
      left: 0;
      color: var(--accent-cyan);
      font-weight: bold;
    }

    /* Metrics Bar */
    .metrics-grid {
      border-top: 1px solid var(--border-color);
      border-bottom: 1px solid var(--border-color);
      background: var(--bg-white);
      padding: 45px 0;
    }

    .metric-item {
      text-align: center;
      padding: 15px;
    }

    .metric-value {
      font-size: 38px;
      font-weight: 800;
      letter-spacing: -0.03em;
      color: var(--bg-dark);
      font-variant-numeric: tabular-nums;
      margin-bottom: 6px;
    }

    .metric-label {
      font-size: 13px;
      color: var(--text-muted);
      font-weight: 500;
    }

    /* Step Card */
    .step-card {
      border: 1px solid var(--border-color);
      background: var(--bg-white);
      border-radius: var(--radius-md);
      padding: 32px 24px;
      position: relative;
      height: 100%;
    }

    .step-number {
      font-size: 12px;
      font-weight: 800;
      color: var(--accent-indigo);
      background: #EEF2FF;
      display: inline-block;
      padding: 2px 8px;
      border-radius: 4px;
      margin-bottom: 14px;
    }

    /* Testimonial Quote */
    .quote-card {
      background: var(--bg-white);
      border: 1px solid var(--border-color);
      border-radius: var(--radius-md);
      padding: 28px;
      height: 100%;
      display: flex;
      flex-direction: column;
      justify-content: space-between;
    }

    .quote-text {
      font-size: 14px;
      color: var(--text-muted);
      line-height: 1.7;
      margin-bottom: 20px;
    }

    .author-name {
      font-size: 14px;
      font-weight: 700;
      color: var(--text-main);
    }

    .author-role {
      font-size: 12px;
      color: var(--text-light);
    }

    /* Changelog Timeline */
    .changelog-item {
      border-left: 2px solid var(--border-color);
      padding-left: 24px;
      margin-bottom: 30px;
      position: relative;
    }

    .changelog-item::before {
      content: '';
      position: absolute;
      left: -6px;
      top: 4px;
      width: 10px;
      height: 10px;
      border-radius: 50%;
      background: var(--accent-indigo);
    }

    .changelog-version {
      font-size: 13px;
      font-weight: 700;
      color: var(--accent-indigo);
      margin-bottom: 4px;
    }

    /* Dark Deep Dive Section */
    .dark-inner-box {
      background: var(--bg-dark-card);
      border: 1px solid var(--border-dark);
      border-radius: var(--radius-lg);
      padding: 40px;
    }

    /* Contact / CTA Block */
    .cta-card {
      background: linear-gradient(135deg, #0B0F19 0%, #1E1B4B 100%);
      border-radius: var(--radius-lg);
      padding: 60px 40px;
      color: #FFFFFF;
      border: 1px solid rgba(255, 255, 255, 0.1);
    }

    .form-control-custom {
      width: 100%;
      padding: 12px 16px;
      background: rgba(255, 255, 255, 0.08);
      border: 1px solid rgba(255, 255, 255, 0.2);
      border-radius: var(--radius-sm);
      color: #fff;
      font-size: 14px;
      margin-bottom: 16px;
      outline: none;
    }

    .form-control-custom:focus {
      border-color: var(--accent-cyan);
      background: rgba(255, 255, 255, 0.12);
    }

    /* Footer */
    footer {
      background-color: #060911;
      color: var(--text-light);
      padding: 70px 0 35px;
      border-top: 1px solid rgba(255, 255, 255, 0.08);
      font-size: 13px;
    }

    .footer-title {
      font-size: 14px;
      font-weight: 700;
      color: #FFFFFF;
      margin-bottom: 18px;
    }

    .footer-links {
      list-style: none;
      margin: 0;
    }

    .footer-links li {
      margin-bottom: 10px;
    }

    .footer-links a:hover {
      color: #FFFFFF;
    }

    .footer-bottom {
      margin-top: 50px;
      padding-top: 24px;
      border-top: 1px solid rgba(255, 255, 255, 0.05);
      text-align: center;
      font-size: 12px;
    }

    /* Responsive */
    @media (max-width: 1024px) {
      .hero-h1 { font-size: 38px; }
      .nav-links { gap: 16px; }
    }

    @media (max-width: 768px) {
      section { padding: 60px 0; }
      .hero-h1 { font-size: 32px; }
      .nav-links { display: none; }
      .top-bar-inner { flex-direction: column; gap: 4px; text-align: center; }
      .cta-card { padding: 36px 20px; }
    }