:root {
    --bg: #050810;
    --surface: #0b1020;
    --accent: #00f5c4;
    --accent2: #7b5cf0;
    --accent3: #f05c7b;
    --text: #e0e8ff;
    --muted: #5a6a9a;
    --border: #1a2444;
    --glow: rgba(0,245,196,0.15);
  }

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

  html { scroll-behavior: smooth; }

  body {
    background: var(--bg);
    color: var(--text);
    font-family: 'Syne', sans-serif;
    overflow-x: hidden;
    cursor: none;
  }

  /* Custom cursor */
  .cursor {
    position: fixed;
    width: 12px; height: 12px;
    background: var(--accent);
    border-radius: 50%;
    pointer-events: none;
    z-index: 9999;
    transition: transform 0.1s;
    mix-blend-mode: screen;
  }
  .cursor-trail {
    position: fixed;
    width: 32px; height: 32px;
    border: 1px solid var(--accent);
    border-radius: 50%;
    pointer-events: none;
    z-index: 9998;
    opacity: 0.5;
    transition: left 0.12s ease, top 0.12s ease;
  }

  /* Canvas background */
  #neural-bg {
    position: fixed;
    inset: 0;
    z-index: 0;
    opacity: 0.4;
  }

  /* Layout */
  .container { max-width: 1200px; margin: 0 auto; padding: 0 2rem; position: relative; z-index: 1; }

  /* NAV */
  nav {
    position: fixed;
    top: 0; left: 0; right: 0;
    z-index: 100;
    padding: 1.2rem 2rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: rgba(5,8,16,0.85);
    backdrop-filter: blur(20px);
    border-bottom: 1px solid var(--border);
  }
  .nav-logo {
    font-family: 'Space Mono', monospace;
    font-size: 1.1rem;
    color: var(--accent);
    letter-spacing: 0.1em;
  }
  .nav-links {
    display: flex;
    gap: 2rem;
    list-style: none;
  }
  .nav-links a {
    font-size: 0.8rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--muted);
    text-decoration: none;
    transition: color 0.2s;
  }
  .nav-links a:hover { color: var(--accent); }

  /* HERO */
  .hero {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    text-align: center;
    padding: 6rem 2rem 4rem;
    position: relative;
    z-index: 1;
  }
  .hero-tag {
    font-family: 'Space Mono', monospace;
    font-size: 0.7rem;
    letter-spacing: 0.2em;
    color: var(--accent);
    text-transform: uppercase;
    border: 1px solid var(--accent);
    padding: 0.4em 1em;
    margin-bottom: 2rem;
    animation: fadeUp 0.6s ease both;
  }
  .hero h1 {
    font-size: clamp(3rem, 8vw, 7rem);
    font-weight: 800;
    line-height: 0.95;
    letter-spacing: -0.03em;
    margin-bottom: 1.5rem;
    animation: fadeUp 0.7s 0.1s ease both;
  }
  .hero h1 span {
    display: block;
    background: linear-gradient(135deg, var(--accent), var(--accent2));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
  }
  .hero-sub {
    font-size: 1.1rem;
    color: var(--muted);
    max-width: 560px;
    line-height: 1.7;
    animation: fadeUp 0.7s 0.2s ease both;
    margin-bottom: 3rem;
  }
  .hero-cta {
    display: flex;
    gap: 1rem;
    animation: fadeUp 0.7s 0.3s ease both;
  }
  .btn {
    padding: 0.85em 2em;
    font-family: 'Space Mono', monospace;
    font-size: 0.8rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    text-decoration: none;
    border: none;
    cursor: pointer;
    transition: all 0.2s;
  }
  .btn-primary {
    background: var(--accent);
    color: #050810;
    font-weight: 700;
  }
  .btn-primary:hover {
    box-shadow: 0 0 30px var(--glow);
    transform: translateY(-2px);
  }
  .btn-outline {
    background: transparent;
    color: var(--text);
    border: 1px solid var(--border);
  }
  .btn-outline:hover { border-color: var(--accent); color: var(--accent); }

  .hero-stats {
    display: flex;
    gap: 4rem;
    margin-top: 5rem;
    animation: fadeUp 0.7s 0.4s ease both;
  }
  .stat-item { text-align: center; }
  .stat-num {
    font-size: 2.5rem;
    font-weight: 800;
    color: var(--accent);
    font-family: 'Space Mono', monospace;
  }
  .stat-label { font-size: 0.75rem; color: var(--muted); letter-spacing: 0.1em; text-transform: uppercase; margin-top: 0.2rem; }

  @keyframes fadeUp {
    from { opacity: 0; transform: translateY(24px); }
    to   { opacity: 1; transform: translateY(0); }
  }

  /* SECTION HEADERS */
  .section { padding: 6rem 0; position: relative; z-index: 1; }
  .section-label {
    font-family: 'Space Mono', monospace;
    font-size: 0.65rem;
    letter-spacing: 0.25em;
    color: var(--accent);
    text-transform: uppercase;
    margin-bottom: 0.8rem;
  }
  .section-title {
    font-size: clamp(2rem, 4vw, 3.5rem);
    font-weight: 800;
    letter-spacing: -0.02em;
    line-height: 1.05;
    margin-bottom: 1.5rem;
  }
  .section-desc {
    color: var(--muted);
    font-size: 1rem;
    max-width: 500px;
    line-height: 1.7;
  }

  /* WHAT IS MCP — INTERACTIVE DIAGRAM */
  .mcp-diagram {
    display: grid;
    grid-template-columns: 1fr auto 1fr;
    gap: 2rem;
    align-items: center;
    margin-top: 4rem;
  }
  .diagram-col {
    display: flex;
    flex-direction: column;
    gap: 1rem;
  }
  .diagram-box {
    background: var(--surface);
    border: 1px solid var(--border);
    padding: 1.2rem 1.5rem;
    cursor: pointer;
    transition: all 0.25s;
    position: relative;
    overflow: hidden;
  }
  .diagram-box::before {
    content: '';
    position: absolute;
    left: 0; top: 0; bottom: 0;
    width: 3px;
    background: var(--accent2);
    transform: scaleY(0);
    transition: transform 0.25s;
  }
  .diagram-box:hover::before, .diagram-box.active::before { transform: scaleY(1); }
  .diagram-box:hover, .diagram-box.active {
    border-color: var(--accent2);
    background: rgba(123,92,240,0.08);
    transform: translateX(4px);
  }
  .diagram-box .box-title {
    font-size: 0.85rem;
    font-weight: 700;
    letter-spacing: 0.05em;
    margin-bottom: 0.25rem;
  }
  .diagram-box .box-sub { font-size: 0.75rem; color: var(--muted); }
  .diagram-box.client-box::before { background: var(--accent); }
  .diagram-box.client-box:hover, .diagram-box.client-box.active { border-color: var(--accent); background: rgba(0,245,196,0.06); }

  .diagram-center {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.5rem;
  }
  .mcp-core {
    width: 140px; height: 140px;
    background: var(--surface);
    border: 2px solid var(--accent);
    border-radius: 50%;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    box-shadow: 0 0 40px rgba(0,245,196,0.2);
    animation: pulse-core 3s ease infinite;
    font-family: 'Space Mono', monospace;
    font-size: 0.75rem;
    font-weight: 700;
    color: var(--accent);
    letter-spacing: 0.1em;
    cursor: default;
    text-align: center;
    line-height: 1.4;
  }
  @keyframes pulse-core {
    0%, 100% { box-shadow: 0 0 40px rgba(0,245,196,0.2); }
    50% { box-shadow: 0 0 60px rgba(0,245,196,0.4); }
  }
  .diagram-connector {
    display: flex;
    flex-direction: column;
    gap: 0.3rem;
    align-items: center;
  }
  .conn-line {
    display: flex;
    align-items: center;
    gap: 4px;
    font-family: 'Space Mono', monospace;
    font-size: 0.6rem;
    color: var(--muted);
  }
  .conn-dot {
    width: 6px; height: 6px;
    border-radius: 50%;
    background: var(--accent);
    animation: blink 1.5s ease infinite;
  }
  @keyframes blink {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.2; }
  }

  /* BEFORE/AFTER TOGGLE */
  .compare-section {
    background: var(--surface);
    border: 1px solid var(--border);
    padding: 3rem;
    margin-top: 4rem;
  }
  .compare-tabs {
    display: flex;
    gap: 0;
    margin-bottom: 2.5rem;
  }
  .compare-tab {
    padding: 0.7em 2em;
    background: none;
    border: 1px solid var(--border);
    color: var(--muted);
    font-family: 'Space Mono', monospace;
    font-size: 0.75rem;
    letter-spacing: 0.1em;
    cursor: pointer;
    transition: all 0.2s;
  }
  .compare-tab.active {
    background: var(--accent);
    color: #050810;
    border-color: var(--accent);
    font-weight: 700;
  }
  .compare-pane { display: none; }
  .compare-pane.active { display: grid; grid-template-columns: 1fr 1fr; gap: 2rem; }
  .compare-card {
    padding: 2rem;
    border: 1px solid var(--border);
    position: relative;
  }
  .compare-card h3 {
    font-size: 1rem;
    font-weight: 700;
    margin-bottom: 1rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
  }
  .compare-card h3 .badge {
    font-family: 'Space Mono', monospace;
    font-size: 0.6rem;
    padding: 0.2em 0.6em;
    letter-spacing: 0.1em;
    text-transform: uppercase;
  }
  .badge-old { background: rgba(240,92,123,0.15); color: var(--accent3); border: 1px solid var(--accent3); }
  .badge-new { background: rgba(0,245,196,0.1); color: var(--accent); border: 1px solid var(--accent); }
  .compare-list { list-style: none; display: flex; flex-direction: column; gap: 0.6rem; }
  .compare-list li {
    font-size: 0.85rem;
    color: var(--muted);
    display: flex;
    align-items: flex-start;
    gap: 0.6rem;
  }
  .compare-list li .icon { font-size: 0.9rem; flex-shrink: 0; margin-top: 1px; }
  .compare-list li .icon.x { color: var(--accent3); }
  .compare-list li .icon.check { color: var(--accent); }

  /* TOPIC EXPLORER — MOSAIC GRID */
  .topic-search {
    display: flex;
    gap: 1rem;
    margin: 2.5rem 0;
    align-items: center;
  }
  .topic-search input {
    flex: 1;
    background: var(--surface);
    border: 1px solid var(--border);
    color: var(--text);
    font-family: 'Space Mono', monospace;
    font-size: 0.85rem;
    padding: 0.8em 1.2em;
    outline: none;
    transition: border-color 0.2s;
  }
  .topic-search input:focus { border-color: var(--accent); }
  .topic-search input::placeholder { color: var(--muted); }

  .filter-pills {
    display: flex;
    flex-wrap: wrap;
    gap: 0.5rem;
    margin-bottom: 2rem;
  }
  .pill {
    padding: 0.35em 0.9em;
    font-family: 'Space Mono', monospace;
    font-size: 0.65rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    border: 1px solid var(--border);
    color: var(--muted);
    background: none;
    cursor: pointer;
    transition: all 0.2s;
  }
  .pill:hover { border-color: var(--accent); color: var(--accent); }
  .pill.active { background: var(--accent); color: #050810; border-color: var(--accent); font-weight: 700; }

  .topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 1.5rem;
  }
  .topic-card {
    background: var(--surface);
    border: 1px solid var(--border);
    padding: 1.5rem;
    cursor: pointer;
    transition: all 0.25s;
    position: relative;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
  }
  .topic-card::after {
    content: '';
    position: absolute;
    inset: 0;
    background: linear-gradient(135deg, transparent, rgba(0,245,196,0.04));
    opacity: 0;
    transition: opacity 0.25s;
  }
  .topic-card:hover::after { opacity: 1; }
  .topic-card:hover {
    border-color: var(--accent);
    transform: translateY(-3px);
    box-shadow: 0 8px 30px rgba(0,0,0,0.4);
  }
  .topic-card.hidden { display: none; }
  .card-num {
    font-family: 'Space Mono', monospace;
    font-size: 0.65rem;
    color: var(--muted);
    letter-spacing: 0.12em;
  }
  .card-title {
    font-size: 1rem;
    font-weight: 700;
    line-height: 1.3;
  }
  .card-tag {
    display: inline-block;
    font-family: 'Space Mono', monospace;
    font-size: 0.6rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    padding: 0.2em 0.7em;
    margin-top: auto;
    border: 1px solid var(--border);
    color: var(--muted);
  }
  .card-tag.mcp { border-color: var(--accent); color: var(--accent); }
  .card-tag.agent { border-color: var(--accent2); color: var(--accent2); }
  .card-tag.security { border-color: var(--accent3); color: var(--accent3); }
  .card-tag.ai { border-color: #f0c05c; color: #f0c05c; }
  .card-arrow {
    position: absolute;
    top: 1.2rem; right: 1.2rem;
    font-size: 1rem;
    color: var(--muted);
    transition: all 0.2s;
    opacity: 0;
  }
  .topic-card:hover .card-arrow { opacity: 1; color: var(--accent); transform: translate(2px,-2px); }

  /* ARCHITECTURE INTERACTIVE */
  .arch-section {
    background: linear-gradient(180deg, transparent, rgba(123,92,240,0.04), transparent);
    padding: 6rem 0;
  }
  .arch-diagram {
    margin-top: 4rem;
    display: grid;
    grid-template-columns: 1fr;
    gap: 0;
  }
  .arch-layer {
    display: grid;
    grid-template-columns: 200px 1fr;
    gap: 0;
    border: 1px solid var(--border);
    border-bottom: none;
    cursor: pointer;
    transition: all 0.2s;
  }
  .arch-layer:last-child { border-bottom: 1px solid var(--border); }
  .arch-layer:hover { background: rgba(123,92,240,0.06); }
  .arch-layer.expanded { background: rgba(123,92,240,0.08); border-color: var(--accent2); }
  .arch-label {
    padding: 1.2rem 1.5rem;
    border-right: 1px solid var(--border);
    display: flex;
    align-items: center;
    gap: 0.7rem;
    font-family: 'Space Mono', monospace;
    font-size: 0.75rem;
    letter-spacing: 0.08em;
    font-weight: 700;
  }
  .arch-icon { font-size: 1.2rem; }
  .arch-content {
    padding: 1.2rem 1.5rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
  }
  .arch-main { font-size: 0.9rem; font-weight: 600; }
  .arch-detail { font-size: 0.78rem; color: var(--muted); margin-top: 0.2rem; max-height: 0; overflow: hidden; transition: max-height 0.3s ease; }
  .arch-layer.expanded .arch-detail { max-height: 200px; }
  .arch-expand { font-size: 1.2rem; color: var(--muted); transition: transform 0.3s; }
  .arch-layer.expanded .arch-expand { transform: rotate(90deg); color: var(--accent2); }

  /* MODAL OVERLAY */
  .modal-overlay {
    position: fixed;
    inset: 0;
    background: rgba(5,8,16,0.9);
    backdrop-filter: blur(10px);
    z-index: 1000;
    display: none;
    align-items: center;
    justify-content: center;
    padding: 2rem;
  }
  .modal-overlay.open { display: flex; }
  .modal {
    background: var(--surface);
    border: 1px solid var(--accent);
    max-width: 600px;
    width: 100%;
    padding: 3rem;
    position: relative;
    box-shadow: 0 0 80px rgba(0,245,196,0.1);
    animation: modalIn 0.3s ease;
  }
  @keyframes modalIn {
    from { opacity: 0; transform: scale(0.96) translateY(10px); }
    to   { opacity: 1; transform: scale(1) translateY(0); }
  }
  .modal-close {
    position: absolute;
    top: 1rem; right: 1.2rem;
    font-family: 'Space Mono', monospace;
    font-size: 1rem;
    color: var(--muted);
    cursor: pointer;
    background: none;
    border: none;
    transition: color 0.2s;
  }
  .modal-close:hover { color: var(--accent3); }
  .modal-num {
    font-family: 'Space Mono', monospace;
    font-size: 0.65rem;
    letter-spacing: 0.2em;
    color: var(--accent);
    margin-bottom: 0.5rem;
  }
  .modal-title { font-size: 1.8rem; font-weight: 800; margin-bottom: 1rem; line-height: 1.2; }
  .modal-body { font-size: 0.9rem; color: var(--muted); line-height: 1.7; margin-bottom: 2rem; }
  .modal-footer { display: flex; gap: 1rem; }
  .modal-tag { font-family: 'Space Mono', monospace; font-size: 0.65rem; letter-spacing: 0.1em; text-transform: uppercase; padding: 0.3em 0.8em; border: 1px solid var(--accent); color: var(--accent); }

  /* FOOTER */
  footer {
    border-top: 1px solid var(--border);
    padding: 3rem 0;
    z-index: 1;
    position: relative;
  }
  .footer-inner {
    display: flex;
    align-items: center;
    justify-content: space-between;
  }
  .footer-brand {
    font-family: 'Space Mono', monospace;
    font-size: 0.9rem;
    color: var(--accent);
  }
  .footer-links { display: flex; gap: 1.5rem; }
  .footer-links a {
    font-family: 'Space Mono', monospace;
    font-size: 0.7rem;
    color: var(--muted);
    text-decoration: none;
    letter-spacing: 0.1em;
    transition: color 0.2s;
  }
  .footer-links a:hover { color: var(--accent); }
  .footer-copy { font-size: 0.75rem; color: var(--muted); }

  /* SCROLL REVEAL */
  .reveal {
    opacity: 0;
    transform: translateY(30px);
    transition: opacity 0.7s ease, transform 0.7s ease;
  }
  .reveal.visible {
    opacity: 1;
    transform: translateY(0);
  }

  /* Divider line */
  .divider {
    height: 1px;
    background: linear-gradient(90deg, transparent, var(--border), transparent);
    margin: 0;
  }

  /* Noise overlay */
  body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='noise'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23noise)' opacity='0.04'/%3E%3C/svg%3E");
    pointer-events: none;
    z-index: 0;
    opacity: 0.5;
  }

  @media (max-width: 768px) {
    .mcp-diagram { grid-template-columns: 1fr; }
    .diagram-center { flex-direction: row; justify-content: center; }
    .compare-pane.active { grid-template-columns: 1fr; }
    .hero-stats { gap: 2rem; }
    .arch-layer { grid-template-columns: 120px 1fr; }
    .footer-inner { flex-direction: column; gap: 1.5rem; text-align: center; }
    .topic-grid { grid-template-columns: 1fr 1fr; }
  }
  @media (max-width: 480px) {
    .topic-grid { grid-template-columns: 1fr; }
    .hero-stats { flex-wrap: wrap; justify-content: center; }
  }