:root {
  --bg: #07090c;
  --surface: #0d1117;
  --line: rgba(255, 255, 255, 0.06);
  --text: #e6e8eb;
  --muted: #8b949e;
  --faint: #4a525c;
  --accent: #ffa94d;
  --accent-hot: #ffd08a;
  --gutter: clamp(16px, 4vw, 48px);
  --hero-pad-bottom: clamp(40px, 8vh, 88px);
  --sans: 'Inter', system-ui, -apple-system, 'Segoe UI', sans-serif;
  --display: 'Space Grotesk', var(--sans);
  --mono: 'JetBrains Mono', ui-monospace, 'SF Mono', Menlo, monospace;
  color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--text);
  font: 400 1.0625rem/1.6 var(--sans);
  -webkit-font-smoothing: antialiased;
  overflow-x: hidden;
}

/* A faint engineering grid that fades out toward the edges. */
body::before {
  content: "";
  position: fixed;
  inset: 0;
  z-index: -2;
  background-image:
    linear-gradient(var(--line) 1px, transparent 1px),
    linear-gradient(90deg, var(--line) 1px, transparent 1px);
  background-size: 56px 56px;
  mask-image: radial-gradient(ellipse 80% 70% at 60% 40%, #000 30%, transparent 100%);
  -webkit-mask-image: radial-gradient(ellipse 80% 70% at 60% 40%, #000 30%, transparent 100%);
}

a {
  color: var(--accent);
  text-decoration: none;
  background-image: linear-gradient(currentColor, currentColor);
  background-size: 0% 1px;
  background-position: 0 100%;
  background-repeat: no-repeat;
  transition: color 0.2s ease, background-size 0.25s ease;
}

a:hover, a:focus-visible {
  color: var(--accent-hot);
  background-size: 100% 1px;
}

a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
  border-radius: 2px;
}

.mono { font-family: var(--mono); }

/* ── Top bar ─────────────────────────────────────────────── */
.topbar {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 16px;
  max-width: 880px;
  width: 100%;
  margin: 0 auto;
  padding: 22px var(--gutter);
  font: 500 0.8125rem/1 var(--mono);
}

.topbar nav { display: flex; gap: clamp(14px, 3vw, 28px); }
.topbar nav a { color: var(--muted); }
.topbar nav a:hover { color: var(--text); }

/* ── Hero ────────────────────────────────────────────────── */
.hero {
  width: 100%;
  max-width: 880px;
  margin: 0 auto;
  padding: clamp(24px, 6vh, 72px) var(--gutter) var(--hero-pad-bottom);
}

.hero-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

/* The cut-out headshot sits on a dark disc inside a grey ring; orange is
   kept for links only. */
.headshot,
.avatar {
  flex: none;
  aspect-ratio: 1;
  object-fit: cover;
  border-radius: 50%;
  border: 2px solid var(--muted);
  background: radial-gradient(circle at 50% 30%, #1f242c, var(--surface) 70%);
  box-shadow: 0 0 0 6px rgba(139, 148, 158, 0.08);
}

.headshot { width: clamp(120px, 14vw, 168px); height: auto; }

h1 {
  margin: 0;
  font: 600 clamp(2.5rem, 3.6vw + 1rem, 4rem)/1.02 var(--display);
  letter-spacing: -0.03em;
}

h1 .suffix {
  color: var(--muted);
  font-size: 0.62em;
  font-weight: 400;
  letter-spacing: -0.01em;
  white-space: nowrap;
}

.tagline {
  margin: 14px 0 0;
  color: var(--muted);
  font: 400 0.875rem/1.5 var(--mono);
}

.tagline .sep { color: var(--faint); margin: 0 6px; }

.tagline::after {
  content: "▍";
  margin-left: 4px;
  color: var(--accent);
  animation: blink 1.1s steps(1) infinite;
}

.lines {
  list-style: none;
  margin: clamp(20px, 3vh, 28px) 0 0;
  padding: 0;
  border-top: 1px solid var(--line);
}

.lines li {
  padding: 11px 0;
  border-bottom: 1px solid var(--line);
  opacity: 0;
  transform: translateY(6px);
  animation: rise 0.5s ease forwards;
  animation-delay: calc(var(--i) * 60ms + 150ms);
}

.path {
  font: 400 0.875em/1 var(--mono);
  color: var(--muted);
  white-space: nowrap;
}


/* ── Portrait ────────────────────────────────────────────── */
/* ── Small screens: the headshot moves above the name ─────── */
@media (max-width: 640px) {
  .hero-head {
    flex-direction: column-reverse;
    align-items: flex-start;
    gap: 20px;
  }

  .headshot { width: 112px; }
}

@media (max-width: 480px) {
  body { font-size: 1rem; }
  h1 { font-size: clamp(1.75rem, 8.4vw, 2.5rem); }
  .path { white-space: normal; }
}

@keyframes rise { to { opacity: 1; transform: none; } }
@keyframes blink { 50% { opacity: 0; } }

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation: none !important; transition: none !important; }
  .lines li { opacity: 1; transform: none; }
}

/* ── Bio page ────────────────────────────────────────────── */
.doc {
  flex: 1;
  width: 100%;
  max-width: 880px;
  margin: 0 auto;
  padding: clamp(16px, 4vh, 40px) var(--gutter) 96px;
}

.doc-head {
  display: flex;
  align-items: center;
  gap: 20px;
}

.avatar { width: 88px; height: 88px; }

.doc h1 { font-size: clamp(1.75rem, 2.5vw + 1rem, 2.75rem); }
.doc .tagline { margin-top: 8px; }

.lead {
  margin: 40px 0 0;
  font-size: 1.15rem;
  line-height: 1.65;
}

.doc-section {
  margin-top: 56px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}

.doc-section h2 {
  margin: 0 0 20px;
  color: var(--accent);
  font: 500 0.75rem/1.4 var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.doc-section h2 .count {
  margin-left: 10px;
  color: var(--muted);
  letter-spacing: 0;
  text-transform: none;
}

.prose p { margin: 0 0 14px; color: #c9cdd2; }
.prose p:last-child { margin-bottom: 0; }

.entries { list-style: none; margin: 0; padding: 0; }

.entries li {
  display: grid;
  grid-template-columns: 4rem 1fr;
  gap: 16px;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}

.entries li:first-child { padding-top: 0; }
.entries li:last-child { border-bottom: 0; }

.year {
  padding-top: 0.15em;
  color: var(--muted);
  font: 500 0.8125rem/1.6 var(--mono);
}

.entries p { margin: 0; }
.entries .title { font-weight: 500; line-height: 1.45; }

.entries .authors {
  margin-top: 4px;
  color: var(--muted);
  font-size: 0.875rem;
  line-height: 1.5;
}

.entries .authors b { color: var(--text); font-weight: 500; }

.entries .meta {
  margin-top: 4px;
  color: var(--muted);
  font: 400 0.8125rem/1.5 var(--mono);
}

@media (max-width: 480px) {
  .doc-head { gap: 14px; }
  .avatar { width: 64px; height: 64px; }
  .lead { margin-top: 28px; font-size: 1.05rem; }
  .doc-section { margin-top: 40px; }
  .entries li { grid-template-columns: 1fr; gap: 2px; }
}

/* ── Puzzles ─────────────────────────────────────────────── */
.label {
  margin: 0 0 14px;
  color: var(--accent);
  font: 500 0.75rem/1.4 var(--mono);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.doc .lede { margin: 16px 0 0; color: var(--muted); font-size: 1.05rem; }

.statement {
  margin: 28px 0 0;
  font-size: 1.2rem;
  line-height: 1.55;
}

.statement .katex-display { font-size: 1.25em; }

/* Long equations scroll sideways on phones instead of breaking the column. */
.katex-display {
  overflow-x: auto;
  overflow-y: hidden;
  margin: 20px 0;
  padding: 4px 0;
}

.katex { color: var(--text); }

.figure {
  margin: 32px 0;
  padding: clamp(14px, 3vw, 24px);
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(13, 17, 23, 0.7);
}

.figure svg, .figure canvas { display: block; width: 100%; height: auto; }

.figure figcaption {
  margin-top: 14px;
  color: var(--muted);
  font: 400 0.8125rem/1.6 var(--mono);
}

.controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 18px;
  margin-bottom: 16px;
}

.controls .group { display: flex; align-items: center; gap: 8px; }
.controls .group > span { color: var(--muted); font: 400 0.8125rem/1 var(--mono); }

.btn {
  padding: 7px 12px;
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 8px;
  background: transparent;
  color: var(--text);
  font: 500 0.8125rem/1 var(--mono);
  cursor: pointer;
  transition: border-color 0.2s ease, color 0.2s ease, background 0.2s ease;
}

.btn:hover { border-color: var(--accent); color: var(--accent-hot); }
.btn[aria-pressed="true"] { border-color: var(--accent); background: rgba(255, 169, 77, 0.12); color: var(--accent); }
.btn:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.status {
  min-height: 1.6em;
  margin-top: 12px;
  font: 500 0.875rem/1.6 var(--mono);
}

.status.good { color: #7ee2b8; }
.status.bad { color: #ff8a7a; }

details.solution { margin-top: 40px; }

details.solution > summary {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  padding: 11px 18px;
  border: 1px solid var(--accent);
  border-radius: 10px;
  color: var(--accent);
  font: 500 0.875rem/1 var(--mono);
  cursor: pointer;
  list-style: none;
  transition: background 0.2s ease;
}

details.solution > summary::-webkit-details-marker { display: none; }
details.solution > summary::before { content: "▸"; transition: transform 0.2s ease; }
details.solution[open] > summary::before { transform: rotate(90deg); }
details.solution > summary:hover { background: rgba(255, 169, 77, 0.08); }
details.solution > summary .when-open { display: none; }
details.solution[open] > summary .when-open { display: inline; }
details.solution[open] > summary .when-closed { display: none; }
details.solution[open] > .prose { animation: reveal 0.45s ease both; }

@keyframes reveal { from { opacity: 0; transform: translateY(8px); } }

details.solution > .prose { margin-top: 28px; }

.prose { line-height: 1.7; }
.prose em { color: var(--text); }

.prose blockquote {
  margin: 20px 0;
  padding: 4px 0 4px 18px;
  border-left: 2px solid var(--accent);
  color: #c9cdd2;
  font-style: italic;
}

.prose blockquote cite {
  display: block;
  margin-top: 8px;
  color: var(--muted);
  font: normal 400 0.8125rem/1.5 var(--mono);
}

.note {
  margin-top: 32px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-style: italic;
}

/* Puzzles index */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
  margin-top: 36px;
}

.card {
  display: flex;
  flex-direction: column;
  gap: 12px;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: rgba(13, 17, 23, 0.7);
  color: var(--text);
  background-image: none;
  transition: border-color 0.25s ease, transform 0.25s ease;
}

.card:hover, .card:focus-visible {
  border-color: rgba(255, 169, 77, 0.5);
  color: var(--text);
  transform: translateY(-2px);
}

.card .label { margin: 0; }
.card h2, .card h3 { margin: 0; font: 600 1.25rem/1.25 var(--display); letter-spacing: -0.01em; }
.card p { margin: 0; color: var(--muted); font-size: 0.9375rem; line-height: 1.55; }
.card .go { margin-top: auto; color: var(--accent); font: 500 0.8125rem/1 var(--mono); }
.card svg { width: 100%; height: 120px; }

.motif-spin { transform-box: view-box; transform-origin: 50% 50%; animation: spin 6s linear infinite; }
.motif-blink { animation: blink-bit 3.2s steps(1) infinite; }
.motif-blink.b2 { animation-delay: -1.1s; }
.motif-blink.b3 { animation-delay: -2.2s; }

/* Homepage teaser of the puzzles */
.home-section { margin-top: 56px; }
.home-section .label { margin: 0; }
.home-section .lede { margin: 10px 0 0; color: var(--muted); }
.home-section .cards { margin-top: 18px; }
.cards.compact .card { padding: 16px 18px 18px; gap: 10px; }
.cards.compact .card svg { height: 96px; }

@keyframes spin { to { transform: rotate(360deg); } }
@keyframes blink-bit { 0%, 49% { fill: var(--accent); } 50%, 100% { fill: #2a313b; } }

/* Logic puzzle */
.bits { display: flex; gap: 10px; }

.bit {
  min-width: 52px;
  padding: 10px 0;
  border: 1px solid rgba(255, 255, 255, 0.14);
  border-radius: 10px;
  background: #11161d;
  color: var(--muted);
  font: 600 1rem/1 var(--mono);
  cursor: pointer;
  transition: all 0.2s ease;
}

.bit[aria-pressed="true"] {
  border-color: var(--accent);
  background: rgba(255, 169, 77, 0.16);
  color: var(--accent-hot);
  box-shadow: 0 0 18px rgba(255, 169, 77, 0.25);
}

.bit .v { display: block; margin-top: 6px; font-size: 0.75rem; font-weight: 400; }

.pipeline { display: grid; gap: 12px; }

.stage {
  display: grid;
  grid-template-columns: 1fr auto;
  align-items: center;
  gap: 12px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 10px;
  transition: border-color 0.25s ease, background 0.25s ease;
}

.stage .name { color: var(--muted); font: 500 0.75rem/1.4 var(--mono); letter-spacing: 0.04em; }
.stage .expr { margin-top: 4px; overflow-x: auto; }

.lamp {
  min-width: 34px;
  padding: 6px 0;
  border-radius: 999px;
  background: #1a2029;
  color: var(--faint);
  text-align: center;
  font: 600 0.8125rem/1 var(--mono);
  transition: all 0.25s ease;
}

.stage.on { border-color: rgba(255, 169, 77, 0.45); background: rgba(255, 169, 77, 0.05); }
.stage.on .lamp { background: var(--accent); color: #1a1206; box-shadow: 0 0 14px rgba(255, 169, 77, 0.5); }

.flow { color: var(--faint); text-align: center; font: 400 0.75rem/1 var(--mono); }

.outs { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; }

.tt { width: 100%; margin-top: 18px; border-collapse: collapse; font: 400 0.8125rem/1 var(--mono); text-align: center; }
.tt th { padding: 8px 4px; color: var(--muted); font-weight: 500; border-bottom: 1px solid var(--line); }
.tt td { padding: 7px 4px; color: var(--faint); border-bottom: 1px solid var(--line); }
.tt td.one { color: var(--text); }
.tt tr.current td { background: rgba(255, 169, 77, 0.1); color: var(--accent-hot); }
.tt tr.current td.one { color: var(--accent); }

@media (max-width: 480px) {
  .statement { font-size: 1.05rem; }
  .outs { grid-template-columns: 1fr; }
  .bit { min-width: 44px; }
}