:root {
    --ink: #1a1814;
    --ink-mid: #4a4640;
    --ink-light: #9a9490;
    --paper: #f7f4ef;
    --paper-mid: #ede9e2;
    --paper-dark: #ddd8cf;
    --accent: #8b3a2a;
    --accent-light: #c4735f;
    --accent-dim: #f0e0da;
    --rule: #d0cbc2;
    --mono: 'JetBrains Mono', monospace;
    --serif: 'Spectral', Georgia, serif;
    --cond: 'Barlow Condensed', sans-serif;
  }

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

  html { scroll-behavior: smooth; }

  body {
    background: var(--paper);
    color: var(--ink);
    font-family: var(--serif);
    line-height: 1.7;
    min-height: 100vh;
  }

  /* ── Grain overlay ── */
  body::before {
    content: '';
    position: fixed;
    inset: 0;
    background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' 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='0.035'/%3E%3C/svg%3E");
    pointer-events: none;
    z-index: 100;
    opacity: 0.6;
  }

  /* ── Hero ── */
  .hero {
    min-height: 100vh;
    display: grid;
    grid-template-rows: auto 1fr auto;
    border-bottom: 2px solid var(--ink);
    position: relative;
    overflow: hidden;
  }

  /* Background rule lines — like manuscript paper */
  .hero::after {
    content: '';
    position: absolute;
    inset: 0;
    background-image: repeating-linear-gradient(
      to bottom,
      transparent,
      transparent 39px,
      var(--rule) 39px,
      var(--rule) 40px
    );
    opacity: 0.35;
    pointer-events: none;
  }

  .hero-nav {
    padding: 2rem 4rem;
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    position: relative;
    z-index: 2;
    border-bottom: 1px solid var(--rule);
  }

  .nav-wordmark {
    font-family: var(--mono);
    font-size: 0.72rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--ink-light);
  }

  .nav-wordmark em {
    font-style: normal;
    color: var(--accent);
  }

  .nav-meta {
    font-family: var(--mono);
    font-size: 0.65rem;
    color: var(--ink-light);
    letter-spacing: 0.08em;
  }

  .hero-body {
    display: flex;
    flex-direction: column;
    justify-content: center;
    padding: 4rem 4rem 3rem;
    position: relative;
    z-index: 2;
    max-width: 900px;
  }

  .hero-eyebrow {
    font-family: var(--mono);
    font-size: 0.68rem;
    letter-spacing: 0.2em;
    text-transform: uppercase;
    color: var(--accent);
    margin-bottom: 1.5rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
  }

  .hero-eyebrow::before {
    content: '';
    width: 2rem;
    height: 1px;
    background: var(--accent);
  }

  .hero-title {
    font-family: var(--cond);
    font-weight: 300;
    font-size: clamp(3.5rem, 8vw, 7rem);
    line-height: 0.95;
    letter-spacing: -0.02em;
    color: var(--ink);
    margin-bottom: 0.15em;
  }

  .hero-title em {
    font-style: italic;
    font-weight: 300;
    color: var(--accent);
  }

  .hero-subtitle {
    font-family: var(--cond);
    font-weight: 300;
    font-size: clamp(1.4rem, 3vw, 2rem);
    color: var(--ink-mid);
    letter-spacing: 0.02em;
    margin-bottom: 2.5rem;
    font-style: italic;
  }

  .hero-description {
    font-size: 1.05rem;
    color: var(--ink-mid);
    max-width: 640px;
    line-height: 1.75;
    margin-bottom: 3rem;
  }

  .hero-cta {
    display: inline-flex;
    align-items: center;
    gap: 0.75rem;
    background: var(--ink);
    color: var(--paper);
    text-decoration: none;
    padding: 0.85rem 2rem;
    font-family: var(--cond);
    font-size: 1rem;
    font-weight: 600;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    transition: background 0.2s, gap 0.2s;
    border-radius: 2px;
  }

  .hero-cta:hover { background: var(--accent); gap: 1.25rem; }

  .hero-cta-arrow { font-size: 1.1rem; }

  .hero-footer {
    padding: 1.5rem 4rem;
    border-top: 1px solid var(--rule);
    display: flex;
    gap: 3rem;
    position: relative;
    z-index: 2;
  }

  .hero-stat {
    display: flex;
    flex-direction: column;
    gap: 0.1rem;
  }

  .hero-stat-num {
    font-family: var(--cond);
    font-weight: 700;
    font-size: 1.8rem;
    color: var(--ink);
    line-height: 1;
  }

  .hero-stat-label {
    font-family: var(--mono);
    font-size: 0.62rem;
    letter-spacing: 0.1em;
    text-transform: uppercase;
    color: var(--ink-light);
  }

  /* ── Overview section ── */
  .overview {
    padding: 6rem 4rem;
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 4rem;
    border-bottom: 1px solid var(--rule);
    max-width: 1200px;
    margin: 0 auto;
  }

  .overview-label {
    font-family: var(--mono);
    font-size: 0.65rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--ink-light);
    padding-top: 0.4rem;
  }

  .overview-body h2 {
    font-family: var(--cond);
    font-weight: 400;
    font-size: 2rem;
    color: var(--ink);
    margin-bottom: 1.25rem;
    line-height: 1.2;
  }

  .overview-body p {
    font-size: 0.95rem;
    color: var(--ink-mid);
    margin-bottom: 1rem;
    max-width: 640px;
  }

  /* Concept types */
  .concept-types {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1rem;
    margin-top: 2rem;
  }

  .concept-type {
    background: white;
    border: 1px solid var(--rule);
    border-radius: 3px;
    padding: 1.25rem;
    position: relative;
    overflow: hidden;
  }

  .concept-type::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 3px;
    height: 100%;
  }

  .ct-differentiating::before { background: var(--accent); }
  .ct-bridging::before { background: var(--ink); }
  .ct-boundary::before { background: var(--paper-dark); }

  .concept-type-name {
    font-family: var(--cond);
    font-weight: 600;
    font-size: 0.85rem;
    letter-spacing: 0.04em;
    text-transform: uppercase;
    color: var(--ink);
    margin-bottom: 0.5rem;
  }

  .concept-type-desc {
    font-size: 0.78rem;
    color: var(--ink-mid);
    line-height: 1.5;
    font-family: 'Barlow Condensed', sans-serif;
    font-weight: 300;
  }

  /* ── Phase steps ── */
  .phases {
    padding: 6rem 4rem;
    border-bottom: 1px solid var(--rule);
  }

  .phases-header {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 4rem;
    max-width: 1200px;
    margin: 0 auto 4rem;
  }

  .phases-header-label {
    font-family: var(--mono);
    font-size: 0.65rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--ink-light);
    padding-top: 0.4rem;
  }

  .phases-header h2 {
    font-family: var(--cond);
    font-weight: 400;
    font-size: 2rem;
    color: var(--ink);
    line-height: 1.2;
  }

  .phases-grid {
    max-width: 1200px;
    margin: 0 auto;
    display: grid;
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
  }

  .phase-card {
    background: white;
    border: 1px solid var(--rule);
    border-radius: 4px;
    overflow: hidden;
    display: flex;
    flex-direction: column;
    transition: box-shadow 0.2s, transform 0.2s;
    text-decoration: none;
    color: inherit;
    animation: fadeUp 0.5s ease both;
  }

  .phase-card:nth-child(1) { animation-delay: 0.1s; }
  .phase-card:nth-child(2) { animation-delay: 0.2s; }
  .phase-card:nth-child(3) { animation-delay: 0.3s; }

  @keyframes fadeUp {
    from { opacity: 0; transform: translateY(16px); }
    to   { opacity: 1; transform: translateY(0); }
  }

  .phase-card:hover {
    box-shadow: 0 8px 32px rgba(26,24,20,0.1);
    transform: translateY(-2px);
  }

  .phase-card-top {
    padding: 1.75rem 1.75rem 1.25rem;
    border-bottom: 1px solid var(--paper-mid);
    display: flex;
    align-items: flex-start;
    gap: 1rem;
  }

  .phase-num {
    font-family: var(--cond);
    font-weight: 700;
    font-size: 3rem;
    line-height: 1;
    color: var(--paper-dark);
    flex-shrink: 0;
    margin-top: -0.1em;
    transition: color 0.2s;
  }

  .phase-card:hover .phase-num { color: var(--accent); }

  .phase-card-meta {}

  .phase-tag-label {
    font-family: var(--mono);
    font-size: 0.6rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--ink-light);
    margin-bottom: 0.3rem;
  }

  .phase-name {
    font-family: var(--cond);
    font-weight: 600;
    font-size: 1.2rem;
    color: var(--ink);
    line-height: 1.2;
  }

  .phase-card-body {
    padding: 1.25rem 1.75rem;
    flex: 1;
  }

  .phase-desc {
    font-size: 0.85rem;
    color: var(--ink-mid);
    line-height: 1.6;
    margin-bottom: 1rem;
  }

  .phase-steps {
    list-style: none;
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
  }

  .phase-steps li {
    display: flex;
    align-items: baseline;
    gap: 0.5rem;
    font-family: var(--mono);
    font-size: 0.68rem;
    color: var(--ink-light);
    letter-spacing: 0.02em;
  }

  .phase-steps li::before {
    content: '→';
    color: var(--accent);
    flex-shrink: 0;
  }

  .phase-card-footer {
    padding: 1rem 1.75rem;
    border-top: 1px solid var(--paper-mid);
    display: flex;
    align-items: center;
    justify-content: space-between;
  }

  .phase-io {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
  }

  .io-chip {
    font-family: var(--mono);
    font-size: 0.58rem;
    letter-spacing: 0.06em;
    text-transform: uppercase;
    padding: 0.15rem 0.45rem;
    border-radius: 2px;
  }

  .io-in  { background: var(--paper-mid); color: var(--ink-light); }
  .io-out { background: var(--accent-dim); color: var(--accent); }

  .phase-link-arrow {
    font-size: 1rem;
    color: var(--ink-light);
    transition: color 0.2s, transform 0.2s;
  }

  .phase-card:hover .phase-link-arrow { color: var(--accent); transform: translateX(4px); }

  /* ── Workflow diagram ── */
  .workflow {
    padding: 5rem 4rem;
    background: var(--ink);
    color: var(--paper);
    border-bottom: 2px solid var(--ink);
  }

  .workflow-inner {
    max-width: 1200px;
    margin: 0 auto;
  }

  .workflow-label {
    font-family: var(--mono);
    font-size: 0.65rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--ink-light);
    margin-bottom: 2.5rem;
    display: flex;
    align-items: center;
    gap: 0.75rem;
  }

  .workflow-label::after {
    content: '';
    flex: 1;
    height: 1px;
    background: #333;
  }

  .workflow-flow {
    display: flex;
    align-items: stretch;
    gap: 0;
    overflow-x: auto;
    padding-bottom: 0.5rem;
  }

  .flow-step {
    flex: 1;
    min-width: 140px;
    padding: 1.5rem;
    border-right: 1px solid #333;
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
  }

  .flow-step:last-child { border-right: none; }

  .flow-step-phase {
    font-family: var(--mono);
    font-size: 0.58rem;
    letter-spacing: 0.12em;
    text-transform: uppercase;
    color: var(--accent-light);
  }

  .flow-step-name {
    font-family: var(--cond);
    font-weight: 600;
    font-size: 1rem;
    color: var(--paper);
    line-height: 1.2;
  }

  .flow-step-desc {
    font-size: 0.75rem;
    color: #888;
    line-height: 1.5;
    font-family: var(--cond);
    font-weight: 300;
    flex: 1;
  }

  .flow-step-output {
    font-family: var(--mono);
    font-size: 0.6rem;
    color: var(--accent-light);
    letter-spacing: 0.05em;
    margin-top: auto;
    padding-top: 0.75rem;
    border-top: 1px solid #2a2a2a;
  }

  /* ── Output types ── */
  .outputs-section {
    padding: 6rem 4rem;
    border-bottom: 1px solid var(--rule);
    max-width: 1200px;
    margin: 0 auto;
  }

  .outputs-grid {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 4rem;
  }

  .outputs-label {
    font-family: var(--mono);
    font-size: 0.65rem;
    letter-spacing: 0.15em;
    text-transform: uppercase;
    color: var(--ink-light);
    padding-top: 0.4rem;
  }

  .outputs-list {
    display: flex;
    flex-direction: column;
    gap: 1rem;
  }

  .output-item {
    display: grid;
    grid-template-columns: auto 1fr;
    gap: 1rem;
    align-items: start;
    padding: 1rem 0;
    border-bottom: 1px solid var(--paper-mid);
  }

  .output-item:last-child { border-bottom: none; }

  .output-stage {
    font-family: var(--mono);
    font-size: 0.62rem;
    letter-spacing: 0.08em;
    text-transform: uppercase;
    background: var(--paper-mid);
    color: var(--ink-light);
    padding: 0.2rem 0.5rem;
    border-radius: 2px;
    white-space: nowrap;
    margin-top: 0.15rem;
  }

  .output-name {
    font-family: var(--cond);
    font-weight: 600;
    font-size: 0.95rem;
    color: var(--ink);
    margin-bottom: 0.2rem;
  }

  .output-desc {
    font-size: 0.8rem;
    color: var(--ink-mid);
    line-height: 1.5;
  }

  /* ── Footer ── */
  footer {
    padding: 2.5rem 4rem;
    border-top: 2px solid var(--ink);
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-wrap: wrap;
    gap: 1rem;
  }

  .footer-wordmark {
    font-family: var(--serif);
    font-style: italic;
    font-size: 1rem;
    color: var(--ink);
  }

  .footer-meta {
    font-family: var(--mono);
    font-size: 0.65rem;
    color: var(--ink-light);
    letter-spacing: 0.08em;
  }

  /* ── Responsive ── */
  @media (max-width: 900px) {
    .hero-nav, .hero-body, .hero-footer { padding-left: 2rem; padding-right: 2rem; }
    .overview, .phases, .phases-header, .phases-grid,
    .workflow, .outputs-section { padding-left: 2rem; padding-right: 2rem; }
    .overview, .outputs-grid { grid-template-columns: 1fr; gap: 2rem; }
    .phases-header { grid-template-columns: 1fr; gap: 1rem; }
    .phases-grid { grid-template-columns: 1fr; }
    .concept-types { grid-template-columns: 1fr; }
    .hero-footer { gap: 1.5rem; }
    footer { padding: 2rem; }
  }