/* roulang page: index */
:root {
      --primary: #0f172a;
      --primary-accent: #2563eb;
      --accent-hover: #1d4ed8;
      --bg-main: #0b0f19;
      --bg-card: #131b2e;
      --bg-card-hover: #1b2640;
      --text-main: #f8fafc;
      --text-muted: #94a3b8;
      --text-dim: #64748b;
      --border: #1e293b;
      --border-accent: #334155;
      --code-bg: #030712;
      --success: #10b981;
      --warning: #f59e0b;
      --danger: #ef4444;
      --font-mono: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, monospace;
      --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    }
    * {
      box-sizing: border-box;
      margin: 0;
      padding: 0;
    }
    body {
      font-family: var(--font-sans);
      background-color: var(--bg-main);
      color: var(--text-main);
      line-height: 1.6;
      -webkit-font-smoothing: antialiased;
    }
    a {
      color: inherit;
      text-decoration: none;
    }
    img {
      max-width: 100%;
      height: auto;
      display: block;
    }
    .container {
      max-width: 1240px;
      margin: 0 auto;
      padding: 0 24px;
    }
    
    /* Header */
    .site-header {
      border-bottom: 1px solid var(--border);
      background: rgba(11, 15, 25, 0.9);
      backdrop-filter: blur(12px);
      position: sticky;
      top: 0;
      z-index: 50;
    }
    .header-inner {
      display: flex;
      align-items: center;
      justify-content: space-between;
      height: 72px;
    }
    .brand-logo {
      display: flex;
      align-items: center;
      gap: 12px;
      font-size: 1.15rem;
      font-weight: 700;
      letter-spacing: -0.02em;
      color: #fff;
    }
    .brand-logo svg {
      color: var(--primary-accent);
      flex-shrink: 0;
    }
    .nav-list {
      display: flex;
      align-items: center;
      gap: 24px;
      list-style: none;
    }
    .nav-link {
      font-size: 0.92rem;
      color: var(--text-muted);
      transition: color 0.2s;
    }
    .nav-link:hover, .nav-link.active {
      color: #fff;
    }
    .btn-header {
      background: #1e293b;
      border: 1px solid var(--border-accent);
      color: #fff;
      font-size: 0.88rem;
      font-weight: 500;
      padding: 8px 18px;
      border-radius: 6px;
      transition: all 0.2s;
    }
    .btn-header:hover {
      background: var(--primary-accent);
      border-color: var(--primary-accent);
    }

    /* Section Base */
    section {
      padding: 80px 0;
      border-bottom: 1px solid var(--border);
    }
    .section-tag {
      display: inline-block;
      font-family: var(--font-mono);
      font-size: 0.78rem;
      text-transform: uppercase;
      letter-spacing: 0.08em;
      color: var(--primary-accent);
      background: rgba(37, 99, 235, 0.1);
      border: 1px solid rgba(37, 99, 235, 0.3);
      padding: 4px 10px;
      border-radius: 4px;
      margin-bottom: 16px;
    }
    .section-title {
      font-size: 2rem;
      font-weight: 700;
      letter-spacing: -0.02em;
      margin-bottom: 16px;
      color: #fff;
    }
    .section-desc {
      font-size: 1.05rem;
      color: var(--text-muted);
      max-width: 840px;
      line-height: 1.7;
    }

    /* Hero */
    .hero-section {
      padding: 60px 0 80px;
      background: radial-gradient(circle at 50% 0%, rgba(37, 99, 235, 0.15) 0%, rgba(11, 15, 25, 0) 70%), url('/assets/images/fd698f297f1642e7.jpg') center/cover no-repeat;
      background-blend-mode: overlay;
      position: relative;
    }
    .hero-grid {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 48px;
      align-items: center;
    }
    .hero-content h1 {
      font-size: 2.5rem;
      line-height: 1.2;
      font-weight: 800;
      letter-spacing: -0.03em;
      margin-bottom: 20px;
    }
    .hero-content p {
      font-size: 1.05rem;
      color: var(--text-muted);
      line-height: 1.75;
      margin-bottom: 32px;
    }
    .hero-actions {
      display: flex;
      gap: 16px;
      margin-bottom: 40px;
    }
    .btn-primary {
      background: var(--primary-accent);
      color: #fff;
      font-weight: 600;
      padding: 12px 28px;
      border-radius: 6px;
      font-size: 0.95rem;
      display: inline-flex;
      align-items: center;
      gap: 8px;
      transition: background 0.2s;
    }
    .btn-primary:hover {
      background: var(--accent-hover);
    }
    .btn-secondary {
      background: transparent;
      border: 1px solid var(--border-accent);
      color: var(--text-main);
      font-weight: 600;
      padding: 12px 24px;
      border-radius: 6px;
      font-size: 0.95rem;
      transition: all 0.2s;
    }
    .btn-secondary:hover {
      background: var(--border);
    }
    
    /* Code Mockup */
    .code-window {
      background: var(--code-bg);
      border: 1px solid var(--border-accent);
      border-radius: 8px;
      box-shadow: 0 20px 40px rgba(0, 0, 0, 0.6);
      overflow: hidden;
      font-family: var(--font-mono);
    }
    .code-header {
      background: #111827;
      padding: 10px 16px;
      display: flex;
      align-items: center;
      gap: 8px;
      border-bottom: 1px solid var(--border);
    }
    .code-dot {
      width: 10px;
      height: 10px;
      border-radius: 50%;
    }
    .dot-red { background: #ef4444; }
    .dot-yellow { background: #f59e0b; }
    .dot-green { background: #10b981; }
    .code-body {
      padding: 20px;
      font-size: 0.85rem;
      line-height: 1.6;
      color: #93c5fd;
      overflow-x: auto;
    }
    .code-keyword { color: #f472b6; }
    .code-str { color: #a7f3d0; }
    .code-num { color: #fde047; }
    .code-comment { color: #64748b; }

    /* Grid Cards */
    .card-grid-3 {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 24px;
      margin-top: 40px;
    }
    .card-grid-4 {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 20px;
      margin-top: 40px;
    }
    .card-grid-2 {
      display: grid;
      grid-template-columns: 1fr 1fr;
      gap: 32px;
      margin-top: 40px;
    }
    .card {
      background: var(--bg-card);
      border: 1px solid var(--border);
      border-radius: 8px;
      padding: 28px;
      transition: all 0.25s ease;
    }
    .card:hover {
      background: var(--bg-card-hover);
      border-color: var(--border-accent);
      transform: translateY(-2px);
    }
    .card-icon {
      width: 44px;
      height: 44px;
      border-radius: 6px;
      background: rgba(37, 99, 235, 0.1);
      display: flex;
      align-items: center;
      justify-content: center;
      color: var(--primary-accent);
      margin-bottom: 20px;
    }
    .card h3 {
      font-size: 1.2rem;
      font-weight: 600;
      margin-bottom: 12px;
      color: #fff;
    }
    .card p {
      font-size: 0.92rem;
      color: var(--text-muted);
      line-height: 1.65;
    }
    
    /* Interactive Flow Step */
    .flow-steps {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 20px;
      margin-top: 40px;
      position: relative;
    }
    .flow-item {
      background: var(--bg-card);
      border: 1px solid var(--border);
      padding: 24px;
      border-radius: 8px;
      position: relative;
    }
    .flow-num {
      font-family: var(--font-mono);
      font-size: 0.85rem;
      font-weight: 700;
      color: var(--primary-accent);
      margin-bottom: 12px;
    }
    .flow-item h4 {
      font-size: 1.1rem;
      margin-bottom: 8px;
      color: #fff;
    }
    .flow-item p {
      font-size: 0.88rem;
      color: var(--text-muted);
      line-height: 1.6;
    }

    /* Telemetry Preview */
    .preview-dashboard {
      background: #020617;
      border: 1px solid var(--border);
      border-radius: 12px;
      padding: 32px;
      margin-top: 40px;
    }
    .dash-row {
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      gap: 20px;
      margin-bottom: 24px;
    }
    .dash-stat {
      background: var(--bg-card);
      border: 1px solid var(--border);
      padding: 20px;
      border-radius: 6px;
    }
    .dash-stat-label {
      font-size: 0.8rem;
      color: var(--text-dim);
      text-transform: uppercase;
      margin-bottom: 8px;
    }
    .dash-stat-value {
      font-size: 1.6rem;
      font-weight: 700;
      color: #fff;
      font-family: var(--font-mono);
    }
    .dash-stat-desc {
      font-size: 0.78rem;
      color: var(--success);
      margin-top: 6px;
    }

    /* Visual Media Cards */
    .media-card {
      background: var(--bg-card);
      border: 1px solid var(--border);
      border-radius: 8px;
      overflow: hidden;
    }
    .media-card img {
      width: 100%;
      height: 200px;
      object-fit: cover;
    }
    .media-card-body {
      padding: 24px;
    }
    .media-card-tag {
      font-size: 0.75rem;
      color: var(--primary-accent);
      font-weight: 600;
      text-transform: uppercase;
      margin-bottom: 8px;
    }

    /* Path timeline */
    .timeline {
      margin-top: 40px;
      border-left: 2px solid var(--border-accent);
      padding-left: 32px;
      margin-left: 12px;
    }
    .timeline-node {
      position: relative;
      margin-bottom: 36px;
    }
    .timeline-node:last-child {
      margin-bottom: 0;
    }
    .timeline-node::before {
      content: "";
      position: absolute;
      left: -39px;
      top: 4px;
      width: 12px;
      height: 12px;
      border-radius: 50%;
      background: var(--primary-accent);
      border: 2px solid var(--bg-main);
    }
    .timeline-title {
      font-size: 1.15rem;
      font-weight: 600;
      margin-bottom: 6px;
      color: #fff;
    }
    .timeline-desc {
      font-size: 0.92rem;
      color: var(--text-muted);
      line-height: 1.65;
    }

    /* Changelog */
    .changelog-item {
      display: flex;
      gap: 24px;
      padding: 20px 0;
      border-bottom: 1px solid var(--border);
    }
    .changelog-ver {
      font-family: var(--font-mono);
      font-size: 0.88rem;
      background: #1e293b;
      color: #38bdf8;
      padding: 4px 10px;
      border-radius: 4px;
      height: fit-content;
      white-space: nowrap;
    }
    .changelog-content h4 {
      font-size: 1.05rem;
      margin-bottom: 6px;
      color: #fff;
    }
    .changelog-content p {
      font-size: 0.9rem;
      color: var(--text-muted);
    }

    /* Final CTA */
    .cta-banner {
      background: linear-gradient(180deg, rgba(37, 99, 235, 0.08) 0%, rgba(15, 23, 42, 0.6) 100%);
      border: 1px solid var(--border-accent);
      border-radius: 12px;
      padding: 60px 40px;
      text-align: center;
      margin: 40px 0 20px;
    }
    .cta-banner h2 {
      font-size: 2.2rem;
      font-weight: 700;
      margin-bottom: 16px;
    }
    .cta-banner p {
      font-size: 1.05rem;
      color: var(--text-muted);
      max-width: 640px;
      margin: 0 auto 32px;
    }

    /* Footer */
    .site-footer {
      background: #060911;
      padding: 60px 0 30px;
      border-top: 1px solid var(--border);
      font-size: 0.88rem;
      color: var(--text-dim);
    }
    .footer-grid {
      display: grid;
      grid-template-columns: 2fr 1fr 1fr 1fr;
      gap: 40px;
      margin-bottom: 48px;
    }
    .footer-brand p {
      margin-top: 12px;
      color: var(--text-muted);
      line-height: 1.6;
      max-width: 320px;
    }
    .footer-col h5 {
      color: #fff;
      font-size: 0.92rem;
      font-weight: 600;
      margin-bottom: 16px;
    }
    .footer-links {
      list-style: none;
    }
    .footer-links li {
      margin-bottom: 10px;
    }
    .footer-links a {
      color: var(--text-muted);
      transition: color 0.2s;
    }
    .footer-links a:hover {
      color: #fff;
    }
    .footer-bottom {
      padding-top: 24px;
      border-top: 1px solid var(--border);
      display: flex;
      justify-content: space-between;
      align-items: center;
      font-size: 0.82rem;
    }

    /* Responsive */
    @media (max-width: 1024px) {
      .hero-grid { grid-template-columns: 1fr; }
      .card-grid-4 { grid-template-columns: repeat(2, 1fr); }
      .card-grid-3 { grid-template-columns: repeat(2, 1fr); }
      .flow-steps { grid-template-columns: repeat(2, 1fr); }
      .dash-row { grid-template-columns: repeat(2, 1fr); }
      .footer-grid { grid-template-columns: 1fr 1fr; }
    }
    @media (max-width: 640px) {
      .section-title { font-size: 1.6rem; }
      .hero-content h1 { font-size: 1.85rem; }
      .card-grid-3, .card-grid-2, .card-grid-4, .flow-steps, .dash-row { grid-template-columns: 1fr; }
      .footer-grid { grid-template-columns: 1fr; }
      .header-inner { height: 60px; }
      .hero-actions { flex-direction: column; }
    }