/* =========================================================================
   Geometry of Intelligence — Design System
   practitioner's argument register · dark-first · single cyan accent
   ========================================================================= */

@import url('https://fonts.googleapis.com/css2?family=IBM+Plex+Serif:ital,wght@0,300;0,400;0,500;0,600;1,400&family=Inter:wght@300;400;500;600;700&family=IBM+Plex+Mono:wght@400;500&display=swap');

:root {
  --canvas: #0a0a0f;
  --canvas-2: #101018;
  --canvas-3: #16161f;
  --ink: #e6e6ec;
  --ink-2: #b4b4c0;
  --ink-3: #7c7c8c;
  --rule: #24242e;
  --rule-2: #34343f;
  --accent: #22d3ee;       /* electric cyan — single accent */
  --accent-dim: #0e7c8c;
  --accent-glow: rgba(34, 211, 238, 0.18);
  --serif: 'IBM Plex Serif', Georgia, 'Times New Roman', serif;
  --sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --mono: 'IBM Plex Mono', 'SF Mono', Menlo, Consolas, monospace;
  --max-w: 68ch;
  --max-w-wide: 92ch;
  --measure: 620px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--canvas);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after {
    animation-duration: 0.001ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.001ms !important;
  }
}

a {
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid var(--rule-2);
  transition: color 120ms ease, border-color 120ms ease;
}
a:hover { color: var(--accent); border-color: var(--accent); }
a.plain { border-bottom: none; }
a.plain:hover { color: var(--accent); }

/* ---- typography ---- */
h1, h2, h3, h4 {
  font-family: var(--serif);
  font-weight: 500;
  letter-spacing: -0.01em;
  color: var(--ink);
}
h1 { font-size: clamp(2.2rem, 4.5vw, 3.6rem); line-height: 1.1; margin: 0 0 1rem; }
h2 { font-size: clamp(1.6rem, 2.6vw, 2.1rem); line-height: 1.2; margin: 3rem 0 1rem; }
h3 { font-size: 1.25rem; line-height: 1.3; margin: 2rem 0 0.6rem; }
h4 { font-size: 1rem; text-transform: uppercase; letter-spacing: 0.08em; color: var(--ink-2); margin: 2rem 0 0.5rem; }

p { margin: 0 0 1.2rem; }
p.lede {
  font-family: var(--serif);
  font-size: 1.25rem;
  line-height: 1.55;
  color: var(--ink);
  font-style: italic;
}
strong { font-weight: 600; color: var(--ink); }
em { font-style: italic; color: var(--ink); }
code, kbd, .mono { font-family: var(--mono); font-size: 0.9em; color: var(--accent); }

blockquote {
  border-left: 2px solid var(--accent);
  padding: 0.4rem 0 0.4rem 1.2rem;
  margin: 1.8rem 0;
  color: var(--ink-2);
  font-family: var(--serif);
  font-style: italic;
}
hr {
  border: 0;
  height: 1px;
  background: var(--rule);
  margin: 3rem auto;
  max-width: var(--measure);
}

/* ---- header ---- */
.site-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  z-index: 40;
  padding: 1rem 1.5rem;
  background: rgba(10, 10, 15, 0.72);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--rule);
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.88rem;
}
.site-header .brand {
  font-family: var(--serif);
  font-weight: 500;
  border-bottom: none;
  letter-spacing: -0.005em;
}
.site-header .brand .dot { color: var(--accent); }
.site-header nav {
  display: flex;
  gap: 1.6rem;
  align-items: center;
}
.site-header nav a {
  border-bottom: none;
  color: var(--ink-2);
  font-size: 0.85rem;
  letter-spacing: 0.02em;
}
.site-header nav a:hover, .site-header nav a.active { color: var(--accent); }
.site-header nav a.applied {
  color: var(--accent);
  padding: 0.3rem 0.7rem;
  border: 1px solid var(--accent-dim);
  border-radius: 2px;
}
.site-header nav a.applied:hover {
  background: var(--accent-glow);
}
@media (max-width: 720px) {
  .site-header nav a:not(.applied):not(.essays) { display: none; }
  .site-header { padding: 0.8rem 1rem; }
}

/* ---- layout ---- */
main { padding-top: 4rem; }
.container {
  max-width: var(--max-w-wide);
  margin: 0 auto;
  padding: 0 1.5rem;
}
.measure {
  max-width: var(--measure);
  margin-left: auto;
  margin-right: auto;
}

/* ---- hero ---- */
.hero {
  position: relative;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  justify-content: center;
  padding: 6rem 1.5rem 4rem;
  overflow: hidden;
}
.hero-canvas {
  position: absolute;
  inset: 0;
  z-index: 0;
  opacity: 0.85;
}
.hero-content {
  position: relative;
  z-index: 1;
  max-width: 780px;
  margin: 0 auto;
}
.hero .eyebrow {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--accent);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  margin-bottom: 1.4rem;
}
.hero h1 {
  font-size: clamp(2.4rem, 5.2vw, 4.4rem);
  line-height: 1.05;
  margin-bottom: 1.4rem;
  font-weight: 400;
}
.hero h1 em {
  color: var(--accent);
  font-style: italic;
  font-family: var(--serif);
}
.hero .subtitle {
  font-family: var(--serif);
  font-size: clamp(1.1rem, 1.8vw, 1.35rem);
  line-height: 1.55;
  color: var(--ink-2);
  max-width: 62ch;
  margin-bottom: 2.4rem;
}
.hero .scroll-hint {
  position: absolute;
  bottom: 2rem;
  left: 50%;
  transform: translateX(-50%);
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-3);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  animation: breathe 4s ease-in-out infinite;
}
@keyframes breathe {
  0%, 100% { opacity: 0.4; }
  50% { opacity: 1; }
}

/* ---- scroll sections ---- */
.scroll-section {
  min-height: 90vh;
  padding: 4rem 1.5rem;
  display: flex;
  align-items: center;
  border-top: 1px solid var(--rule);
  position: relative;
}
.scroll-section .inner {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 3rem;
  max-width: var(--max-w-wide);
  margin: 0 auto;
  width: 100%;
  align-items: center;
}
@media (max-width: 900px) {
  .scroll-section .inner { grid-template-columns: 1fr; }
  .scroll-section { min-height: auto; padding: 3rem 1.5rem; }
}
.scroll-section .text .section-tag {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--accent);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  margin-bottom: 0.8rem;
}
.scroll-section .diagram {
  aspect-ratio: 1 / 1;
  max-width: 460px;
  width: 100%;
  margin: 0 auto;
  border: 1px solid var(--rule);
  background: var(--canvas-2);
  padding: 1.5rem;
  border-radius: 2px;
}
.scroll-section.reverse .inner { direction: rtl; }
.scroll-section.reverse .inner > * { direction: ltr; }
@media (max-width: 900px) {
  .scroll-section.reverse .inner { direction: ltr; }
}

/* ---- bridge / closing ---- */
.bridge {
  border-top: 1px solid var(--rule);
  padding: 6rem 1.5rem 5rem;
  text-align: center;
}
.bridge .measure { text-align: left; }
.bridge h2 { font-size: clamp(1.7rem, 3vw, 2.3rem); }
.bridge .cta {
  display: inline-flex;
  align-items: center;
  gap: 0.6rem;
  margin-top: 1.4rem;
  padding: 0.9rem 1.4rem;
  border: 1px solid var(--accent-dim);
  color: var(--accent);
  font-family: var(--mono);
  font-size: 0.85rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  border-bottom: 1px solid var(--accent-dim);
  transition: all 180ms ease;
}
.bridge .cta:hover {
  background: var(--accent-glow);
  border-color: var(--accent);
  color: var(--accent);
  transform: translateX(2px);
}
.bridge .cta .arrow { transition: transform 180ms ease; }
.bridge .cta:hover .arrow { transform: translateX(4px); }

/* ---- essay hub ---- */
.essay-hub {
  padding: 6rem 1.5rem 4rem;
}
.essay-hub h1 { text-align: center; margin-bottom: 0.6rem; }
.essay-hub .hub-lede {
  text-align: center;
  color: var(--ink-2);
  font-family: var(--serif);
  font-style: italic;
  max-width: 60ch;
  margin: 0 auto 3rem;
}
.essay-graph {
  width: 100%;
  height: 520px;
  border: 1px solid var(--rule);
  background: var(--canvas-2);
  position: relative;
  overflow: hidden;
  max-width: 1000px;
  margin: 0 auto 3rem;
  border-radius: 2px;
}
.essay-graph svg { width: 100%; height: 100%; display: block; }
.essay-graph .node-hit {
  cursor: pointer;
  transition: transform 200ms ease;
}
.essay-graph .node-hit:hover circle { fill: var(--accent); }
.essay-graph .node-hit:hover text { fill: var(--ink); }
.essay-graph .fallback {
  padding: 2rem;
  color: var(--ink-2);
  font-family: var(--serif);
  text-align: center;
}
.essay-list {
  max-width: var(--measure);
  margin: 0 auto;
  list-style: none;
  padding: 0;
}
.essay-list li {
  border-bottom: 1px solid var(--rule);
  padding: 1.4rem 0;
}
.essay-list li:last-child { border-bottom: none; }
.essay-list a {
  display: block;
  border-bottom: none;
}
.essay-list .title {
  font-family: var(--serif);
  font-size: 1.35rem;
  color: var(--ink);
  margin-bottom: 0.3rem;
  transition: color 120ms ease;
}
.essay-list a:hover .title { color: var(--accent); }
.essay-list .thesis {
  color: var(--ink-2);
  font-size: 0.95rem;
  font-family: var(--serif);
  font-style: italic;
}
.essay-list .meta {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-3);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-bottom: 0.5rem;
}

/* ---- essay page ---- */
.essay {
  padding: 5rem 1.5rem 4rem;
}
.essay .essay-head {
  max-width: var(--measure);
  margin: 0 auto 3rem;
  text-align: center;
}
.essay .essay-head .eyebrow {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--accent);
  letter-spacing: 0.2em;
  text-transform: uppercase;
  margin-bottom: 1rem;
}
.essay .essay-head h1 { font-size: clamp(2rem, 3.6vw, 2.8rem); }
.essay .essay-head .thesis {
  font-family: var(--serif);
  font-style: italic;
  color: var(--ink-2);
  font-size: 1.15rem;
  margin-top: 1.2rem;
  line-height: 1.55;
}
.essay-body {
  max-width: var(--measure);
  margin: 0 auto;
  font-family: var(--serif);
  font-size: 1.08rem;
  line-height: 1.75;
}
.essay-body h2 {
  font-size: 1.5rem;
  margin: 3rem 0 1rem;
}
.essay-body p { margin: 0 0 1.4rem; color: var(--ink); }
.essay-body .diagram-wrap {
  margin: 2.5rem -1rem;
  padding: 1.5rem;
  background: var(--canvas-2);
  border: 1px solid var(--rule);
  border-radius: 2px;
}
.essay-body .diagram-wrap svg { width: 100%; height: auto; display: block; }
.essay-body .diagram-caption {
  font-family: var(--sans);
  font-size: 0.82rem;
  color: var(--ink-3);
  text-align: center;
  margin-top: 1rem;
  font-style: normal;
}

/* citation hover */
.citation {
  color: var(--accent);
  border-bottom: 1px dotted var(--accent-dim);
  cursor: help;
  position: relative;
  font-family: var(--mono);
  font-size: 0.85em;
}
.citation:hover { color: var(--accent); }
.citation-trace {
  visibility: hidden;
  opacity: 0;
  position: absolute;
  bottom: 130%;
  left: 50%;
  transform: translateX(-50%);
  min-width: 240px;
  max-width: 320px;
  padding: 0.7rem 0.9rem;
  background: var(--canvas-3);
  border: 1px solid var(--accent-dim);
  border-radius: 2px;
  font-family: var(--sans);
  font-size: 0.8rem;
  font-style: normal;
  color: var(--ink-2);
  line-height: 1.45;
  transition: opacity 180ms ease, transform 180ms ease;
  z-index: 5;
  pointer-events: none;
}
.citation:hover .citation-trace,
.citation:focus .citation-trace {
  visibility: visible;
  opacity: 1;
  transform: translateX(-50%) translateY(-4px);
}

/* essay closing CTA */
.essay-close {
  max-width: var(--measure);
  margin: 4rem auto 0;
  padding: 2rem;
  border: 1px solid var(--rule);
  background: var(--canvas-2);
  border-radius: 2px;
}
.essay-close h4 {
  font-family: var(--mono);
  color: var(--accent);
  font-size: 0.75rem;
  margin: 0 0 0.6rem;
}
.essay-close p {
  font-family: var(--serif);
  color: var(--ink);
  margin-bottom: 0;
}

/* ---- author page ---- */
.author {
  padding: 6rem 1.5rem 4rem;
  max-width: var(--measure);
  margin: 0 auto;
}
.author h1 {
  font-size: clamp(2rem, 3.4vw, 2.6rem);
  margin-bottom: 0.6rem;
}
.author .role {
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--accent);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  margin-bottom: 2.5rem;
}
.author-body {
  font-family: var(--serif);
  font-size: 1.08rem;
  line-height: 1.75;
}
.author-map {
  margin: 3rem 0;
  padding: 2rem;
  background: var(--canvas-2);
  border: 1px solid var(--rule);
  border-radius: 2px;
}
.author-map svg { width: 100%; height: auto; display: block; }

/* ---- paradigm / glossary ---- */
.paradigm {
  padding: 6rem 1.5rem 4rem;
  max-width: var(--measure);
  margin: 0 auto;
}
.paradigm dl { margin: 0; }
.paradigm dt {
  font-family: var(--serif);
  font-size: 1.35rem;
  color: var(--accent);
  margin: 2.5rem 0 0.5rem;
  font-weight: 500;
}
.paradigm dt:first-child { margin-top: 0; }
.paradigm dd {
  margin: 0 0 1rem;
  font-family: var(--serif);
  font-size: 1.05rem;
  line-height: 1.7;
  color: var(--ink);
}
.paradigm dd .anchor {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-3);
  letter-spacing: 0.1em;
  text-transform: uppercase;
  margin-top: 0.4rem;
  display: block;
}

/* ---- footer ---- */
.site-footer {
  border-top: 1px solid var(--rule);
  padding: 3rem 1.5rem 3rem;
  margin-top: 6rem;
  color: var(--ink-3);
  font-size: 0.85rem;
}
.site-footer .foot-inner {
  max-width: var(--max-w-wide);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  gap: 2rem;
  flex-wrap: wrap;
}
.site-footer a { color: var(--ink-2); border-bottom: none; }
.site-footer a:hover { color: var(--accent); }
.site-footer .foot-node {
  font-family: var(--mono);
  font-size: 0.72rem;
  letter-spacing: 0.1em;
  color: var(--ink-3);
}
.site-footer .foot-node .dot { color: var(--accent); }

/* ---- morphing scroll reveal ---- */
.reveal {
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 900ms ease, transform 900ms ease;
}
.reveal.in {
  opacity: 1;
  transform: translateY(0);
}
@media (prefers-reduced-motion: reduce) {
  .reveal { opacity: 1; transform: none; }
}

/* ---- micro utility ---- */
.mono-tag {
  font-family: var(--mono);
  font-size: 0.72rem;
  color: var(--ink-3);
  letter-spacing: 0.14em;
  text-transform: uppercase;
}
.accent { color: var(--accent); }