/* ========================================================================
   Beyond Single-Turn — companion site
   Design tokens and shared styles. Academic-prestige visual register.
   ======================================================================== */

:root {
  /* Palette */
  --ink:            #1a1f2a;       /* primary text */
  --ink-soft:       #2c3343;
  --ink-mute:       #54607a;
  --ink-faint:      #8892a6;
  --rule:           #e3dfd5;
  --rule-soft:      #eeeae0;
  --paper:          #fbfaf6;       /* off-white body */
  --paper-warm:     #f5f1e6;
  --paper-cool:     #f3f1ec;
  --panel:          #ffffff;

  --crimson:        #8b1a2b;       /* muted CMU crimson */
  --crimson-ink:    #5a0f1c;
  --crimson-tint:   #f6e7e8;

  --gold:           #a8833b;
  --gold-tint:      #f4ecd6;

  --sage:           #4f6e62;       /* IF family accent */
  --sage-tint:      #e2ece5;

  --terra:          #a9554c;       /* CE family accent */
  --terra-tint:     #f4e2dc;

  --indigo:         #3a4a79;       /* Methods / improvements */
  --indigo-tint:    #e2e6f1;

  --ochre:          #8a6b2e;       /* Challenges */
  --ochre-tint:     #efe6cf;

  /* Type scale */
  --font-serif:     "Source Serif 4", "Source Serif Pro", "Crimson Pro", "Iowan Old Style", Georgia, serif;
  --font-sans:      "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Helvetica, Arial, sans-serif;
  --font-mono:      "JetBrains Mono", "SFMono-Regular", Menlo, Consolas, monospace;

  --lh-tight:       1.2;
  --lh-body:        1.62;
  --lh-prose:       1.7;

  /* Spacing */
  --space-1: 4px;   --space-2: 8px;   --space-3: 12px;
  --space-4: 16px;  --space-5: 24px;  --space-6: 32px;
  --space-7: 48px;  --space-8: 64px;  --space-9: 96px;

  --radius-xs: 3px;
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 18px;

  --shadow-sm: 0 1px 2px rgba(25, 30, 42, 0.04), 0 1px 3px rgba(25, 30, 42, 0.06);
  --shadow-md: 0 4px 12px rgba(25, 30, 42, 0.07), 0 1px 3px rgba(25, 30, 42, 0.05);
  --shadow-lg: 0 12px 32px rgba(25, 30, 42, 0.10), 0 2px 6px rgba(25, 30, 42, 0.06);

  --measure-narrow: 60ch;
  --measure-body:   72ch;
  --measure-wide:   1200px;
}

/* ---------- Reset & base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16.5px;
  line-height: var(--lh-body);
  font-feature-settings: "kern", "liga", "calt";
  -webkit-font-smoothing: antialiased;
}
img, svg { max-width: 100%; display: block; }
a {
  color: var(--crimson);
  text-decoration: none;
  border-bottom: 1px solid rgba(139, 26, 43, 0.28);
  transition: color 120ms ease, border-color 120ms ease;
}
a:hover { color: var(--crimson-ink); border-bottom-color: var(--crimson-ink); }
a.plain { border-bottom: none; }
a.plain:hover { border-bottom: none; text-decoration: underline; }

code, pre { font-family: var(--font-mono); font-size: 0.94em; }
code {
  background: var(--paper-warm);
  padding: 1px 6px;
  border-radius: var(--radius-xs);
  border: 1px solid var(--rule-soft);
}
pre {
  background: #f7f4ec;
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: var(--space-5);
  overflow: auto;
  line-height: 1.5;
}
pre code { background: transparent; border: none; padding: 0; }

hr.rule {
  border: none;
  border-top: 1px solid var(--rule);
  margin: var(--space-7) 0;
}
hr.ornament {
  border: none;
  height: 18px;
  margin: var(--space-7) 0;
  background-image: radial-gradient(circle, var(--ink-faint) 1.2px, transparent 1.4px);
  background-size: 14px 14px;
  background-position: center;
  background-repeat: repeat-x;
  mask-image: linear-gradient(to right, transparent, black 35%, black 65%, transparent);
  -webkit-mask-image: linear-gradient(to right, transparent, black 35%, black 65%, transparent);
}

/* ---------- Typography ---------- */
h1, h2, h3, h4 {
  font-family: var(--font-serif);
  color: var(--ink);
  line-height: var(--lh-tight);
  letter-spacing: -0.005em;
  margin: 0 0 var(--space-4);
  font-weight: 600;
}
h1 { font-size: clamp(2.1rem, 4.2vw, 3.2rem); letter-spacing: -0.018em; }
h2 { font-size: clamp(1.55rem, 2.6vw, 2.15rem); letter-spacing: -0.012em; margin-top: var(--space-7); }
h3 { font-size: 1.25rem; font-weight: 600; margin-top: var(--space-6); }
h4 { font-size: 1.05rem; font-weight: 600; color: var(--ink-soft); margin-top: var(--space-5); }

.eyebrow {
  font-family: var(--font-sans);
  font-size: 0.72rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--crimson);
  font-weight: 600;
  margin-bottom: var(--space-3);
}
.lead {
  font-family: var(--font-serif);
  font-size: 1.18rem;
  line-height: 1.55;
  color: var(--ink-soft);
  max-width: var(--measure-narrow);
}
.prose { max-width: var(--measure-body); }
.prose p { margin: 0 0 1.1em; }
.prose p:first-of-type::first-letter {
  /* optional drop cap on flagged prose sections */
}
.prose.dropcap > p:first-of-type::first-letter {
  font-family: var(--font-serif);
  font-size: 3.4em;
  float: left;
  line-height: 0.88;
  margin: 0.08em 0.10em 0 0;
  color: var(--crimson);
  font-weight: 600;
}
.prose ul, .prose ol { padding-left: 1.3em; margin: 0 0 1.1em; }
.prose li { margin-bottom: 0.35em; }
.prose blockquote {
  margin: var(--space-5) 0;
  padding: var(--space-3) var(--space-5);
  border-left: 3px solid var(--crimson);
  font-family: var(--font-serif);
  font-style: italic;
  color: var(--ink-soft);
  background: var(--crimson-tint);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

/* ---------- Layout ---------- */
.container {
  width: 100%;
  max-width: var(--measure-wide);
  margin: 0 auto;
  padding: 0 clamp(18px, 3.5vw, 40px);
}
.container-narrow {
  max-width: 920px;
  margin: 0 auto;
  padding: 0 clamp(18px, 3.5vw, 40px);
}
.section { padding: var(--space-8) 0; }
.section-tight { padding: var(--space-7) 0; }
.section-alt { background: var(--paper-warm); border-top: 1px solid var(--rule); border-bottom: 1px solid var(--rule); }
.section-crimson { background: linear-gradient(180deg, var(--crimson-tint) 0%, var(--paper) 100%); }

.grid { display: grid; gap: var(--space-5); }
.grid-2 { grid-template-columns: repeat(auto-fit, minmax(260px, 1fr)); }
.grid-3 { grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); }
.grid-4 { grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); }
.flex { display: flex; gap: var(--space-4); }
.flex-wrap { flex-wrap: wrap; }
.flex-between { justify-content: space-between; align-items: center; }
.flex-center { align-items: center; }

/* ---------- Header / Nav ---------- */
.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background: rgba(251, 250, 246, 0.92);
  backdrop-filter: saturate(1.1) blur(10px);
  -webkit-backdrop-filter: saturate(1.1) blur(10px);
  border-bottom: 1px solid var(--rule);
}
.nav {
  display: flex;
  align-items: center;
  gap: var(--space-5);
  padding: var(--space-3) 0;
  flex-wrap: wrap;
}
.brand {
  display: flex;
  gap: var(--space-3);
  align-items: center;
  font-family: var(--font-serif);
  font-size: 1.05rem;
  color: var(--ink);
  border-bottom: none;
  font-weight: 600;
  letter-spacing: -0.01em;
}
.brand:hover { color: var(--crimson); }
.brand .brand-mark {
  width: 30px; height: 30px; flex: 0 0 30px;
  background: var(--crimson);
  color: #fbfaf6;
  border-radius: 4px;
  display: grid; place-items: center;
  font-family: var(--font-serif);
  font-weight: 700;
  font-size: 0.95rem;
  letter-spacing: -0.02em;
}
.brand small {
  display: block;
  font-family: var(--font-sans);
  font-size: 0.68rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
  font-weight: 500;
  margin-top: 1px;
}
.nav-links {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: var(--space-5);
  list-style: none;
  padding: 0;
  flex-wrap: wrap;
}
.nav-links a {
  color: var(--ink-soft);
  border-bottom: none;
  font-size: 0.93rem;
  padding: 4px 0;
  border-bottom: 2px solid transparent;
  transition: color 120ms ease, border-color 120ms ease;
}
.nav-links a:hover { color: var(--crimson); }
.nav-links a.active {
  color: var(--crimson);
  border-bottom-color: var(--crimson);
}
.nav-cta {
  background: var(--crimson);
  color: #fff !important;
  padding: 7px 14px;
  border-radius: var(--radius-sm);
  border-bottom: none !important;
  font-size: 0.88rem;
  font-weight: 500;
  transition: background 160ms ease, transform 120ms ease;
}
.nav-cta:hover { background: var(--crimson-ink); transform: translateY(-1px); }
.nav-toggle {
  display: none;
  background: none; border: 1px solid var(--rule);
  border-radius: 6px; padding: 6px 10px;
  font-size: 1rem; cursor: pointer;
  margin-left: auto;
}
@media (max-width: 820px) {
  .nav-toggle { display: block; }
  .nav-links {
    display: none;
    width: 100%;
    flex-direction: column;
    align-items: flex-start;
    gap: var(--space-2);
    padding: var(--space-4) 0;
  }
  .nav-links.open { display: flex; }
}

/* ---------- Hero ---------- */
.hero {
  padding: clamp(56px, 9vw, 120px) 0 clamp(40px, 6vw, 72px);
  position: relative;
  overflow: hidden;
}
.hero::before {
  content: '';
  position: absolute; inset: 0;
  background:
    radial-gradient(ellipse 60% 45% at 15% 10%, rgba(139, 26, 43, 0.07), transparent 60%),
    radial-gradient(ellipse 50% 40% at 85% 20%, rgba(168, 131, 59, 0.09), transparent 60%);
  pointer-events: none;
}
.hero-inner { position: relative; }
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  background: var(--panel);
  border: 1px solid var(--rule);
  padding: 5px 12px 5px 8px;
  border-radius: 999px;
  font-size: 0.78rem;
  color: var(--ink-soft);
  letter-spacing: 0.01em;
  margin-bottom: var(--space-5);
  box-shadow: var(--shadow-sm);
}
.hero-badge .dot {
  width: 7px; height: 7px; border-radius: 50%;
  background: var(--crimson);
  box-shadow: 0 0 0 3px rgba(139, 26, 43, 0.16);
}
.hero-title {
  font-size: clamp(2.3rem, 5.2vw, 4rem);
  line-height: 1.05;
  margin-bottom: var(--space-4);
  max-width: 18ch;
  letter-spacing: -0.022em;
}
.hero-title em {
  font-style: italic;
  color: var(--crimson);
}
.hero-sub {
  font-family: var(--font-serif);
  color: var(--ink-soft);
  font-size: clamp(1.1rem, 1.8vw, 1.35rem);
  line-height: 1.5;
  max-width: 58ch;
  margin-bottom: var(--space-6);
}
.hero-authors {
  font-size: 0.92rem;
  color: var(--ink-mute);
  margin-bottom: var(--space-3);
}
.hero-authors strong { color: var(--ink-soft); font-weight: 500; }
.hero-affil {
  font-size: 0.86rem;
  color: var(--ink-faint);
  margin-bottom: var(--space-6);
  font-style: italic;
}
.hero-cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3);
}

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  font-family: var(--font-sans);
  font-size: 0.93rem;
  font-weight: 500;
  letter-spacing: 0.005em;
  border-bottom: none !important;
  transition: all 140ms ease;
  cursor: pointer;
  border: 1px solid transparent;
}
.btn-primary {
  background: var(--crimson);
  color: #fff !important;
}
.btn-primary:hover { background: var(--crimson-ink); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-outline {
  background: var(--panel);
  color: var(--ink) !important;
  border-color: var(--rule);
}
.btn-outline:hover { border-color: var(--ink-mute); background: var(--paper-warm); }
.btn-ghost {
  background: transparent;
  color: var(--ink-soft) !important;
}
.btn-ghost:hover { background: var(--paper-warm); }
.btn-small { padding: 6px 12px; font-size: 0.85rem; }

/* ---------- Chips ---------- */
.chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 500;
  letter-spacing: 0.01em;
  border: 1px solid var(--rule);
  background: var(--panel);
  color: var(--ink-soft);
}
.chip.chip-if { background: var(--sage-tint); color: #324b41; border-color: #cadbce; }
.chip.chip-ce { background: var(--terra-tint); color: #7d3a32; border-color: #e9c9c1; }
.chip.chip-meth { background: var(--indigo-tint); color: #2b3960; border-color: #c9d1e4; }
.chip.chip-chal { background: var(--ochre-tint); color: #6a5220; border-color: #ddcea3; }
.chip.chip-gold { background: var(--gold-tint); color: #6a5220; border-color: #e2d5ac; }

/* ---------- Cards ---------- */
.card {
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: var(--space-5);
  transition: border-color 160ms ease, transform 160ms ease, box-shadow 160ms ease;
  position: relative;
}
.card:hover { border-color: var(--ink-mute); transform: translateY(-2px); box-shadow: var(--shadow-md); }
.card-accent-if { border-top: 3px solid var(--sage); }
.card-accent-ce { border-top: 3px solid var(--terra); }
.card-accent-meth { border-top: 3px solid var(--indigo); }
.card-accent-chal { border-top: 3px solid var(--ochre); }
.card-accent-crimson { border-top: 3px solid var(--crimson); }
.card h3 { margin-top: 0; font-size: 1.1rem; }
.card .muted { color: var(--ink-mute); font-size: 0.92rem; }
.card-link {
  display: inline-flex; gap: 4px; align-items: center;
  margin-top: var(--space-3);
  font-size: 0.88rem;
  color: var(--crimson);
  font-weight: 500;
  border-bottom: none;
}
.card-link:hover { gap: 8px; }

.stat {
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: var(--space-5);
  text-align: left;
}
.stat-num {
  font-family: var(--font-serif);
  font-size: clamp(2rem, 3.2vw, 2.6rem);
  color: var(--crimson);
  line-height: 1;
  font-weight: 600;
  letter-spacing: -0.02em;
}
.stat-label {
  font-size: 0.82rem;
  color: var(--ink-mute);
  margin-top: var(--space-2);
  text-transform: uppercase;
  letter-spacing: 0.08em;
}
.stat-sub {
  font-size: 0.9rem;
  color: var(--ink-soft);
  margin-top: var(--space-2);
  max-width: 28ch;
}

/* ---------- Pillar / accent sections ---------- */
.pillar {
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  position: relative;
  overflow: hidden;
}
.pillar::before {
  content: ""; position: absolute;
  top: 0; left: 0; right: 0; height: 4px;
  background: var(--accent, var(--crimson));
}
.pillar.if { --accent: var(--sage); }
.pillar.ce { --accent: var(--terra); }
.pillar.meth { --accent: var(--indigo); }
.pillar.chal { --accent: var(--ochre); }
.pillar .pillar-num {
  font-family: var(--font-serif);
  font-size: 2rem;
  font-weight: 600;
  color: var(--accent, var(--crimson));
  line-height: 1;
  margin-bottom: var(--space-3);
}
.pillar h3 { margin-top: 0; }

/* ---------- Tables ---------- */
.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  background: var(--panel);
}
table.data {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.9rem;
}
table.data thead th {
  background: var(--paper-warm);
  border-bottom: 2px solid var(--rule);
  padding: 10px 12px;
  text-align: left;
  font-weight: 600;
  color: var(--ink-soft);
  white-space: nowrap;
  position: sticky;
  top: 0;
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  cursor: pointer;
  user-select: none;
}
table.data thead th.sort-asc::after  { content: "  ↑"; color: var(--crimson); }
table.data thead th.sort-desc::after { content: "  ↓"; color: var(--crimson); }
table.data tbody td {
  padding: 10px 12px;
  border-bottom: 1px solid var(--rule-soft);
  vertical-align: top;
}
table.data tbody tr:nth-child(even) td { background: #fcfaf5; }
table.data tbody tr:hover td { background: var(--crimson-tint); }
table.data tbody tr:last-child td { border-bottom: none; }
table.data .num { font-variant-numeric: tabular-nums; text-align: right; white-space: nowrap; }
table.data .cm { color: #1f6b3d; font-weight: 600; }
table.data .xm { color: #9b3540; font-weight: 600; }

.table-caption {
  font-size: 0.82rem;
  color: var(--ink-mute);
  margin-top: var(--space-3);
  font-style: italic;
}

/* ---------- Filters / controls ---------- */
.controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-4);
}
.control-input, .control-select {
  padding: 8px 12px;
  border: 1px solid var(--rule);
  border-radius: var(--radius-sm);
  background: var(--panel);
  font-family: inherit;
  font-size: 0.9rem;
  color: var(--ink);
  min-height: 38px;
}
.control-input:focus, .control-select:focus {
  outline: 2px solid rgba(139, 26, 43, 0.2);
  border-color: var(--crimson);
}
.control-input {
  flex: 1 1 240px;
  min-width: 200px;
}
.control-label {
  font-size: 0.78rem;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--ink-mute);
  margin-right: var(--space-1);
  font-weight: 500;
}
.facet-group {
  display: inline-flex;
  border: 1px solid var(--rule);
  border-radius: 999px;
  background: var(--panel);
  padding: 3px;
}
.facet-group button {
  background: transparent;
  border: none;
  padding: 5px 12px;
  border-radius: 999px;
  font-size: 0.82rem;
  color: var(--ink-mute);
  cursor: pointer;
  font-family: inherit;
}
.facet-group button.active {
  background: var(--crimson);
  color: #fff;
}
.count-chip {
  font-size: 0.8rem;
  color: var(--ink-mute);
  margin-left: auto;
}

/* ---------- Taxonomy tree ---------- */
.tax-wrap {
  display: grid;
  grid-template-columns: 1fr 340px;
  gap: var(--space-6);
  align-items: start;
}
@media (max-width: 980px) { .tax-wrap { grid-template-columns: 1fr; } }

.tax-canvas {
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: var(--space-5);
  overflow: hidden;
  position: relative;
  min-height: 640px;
}
.tax-canvas svg { width: 100%; height: auto; }

.tax-panel {
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: var(--space-5);
  position: sticky;
  top: 78px;
  min-height: 360px;
}
.tax-panel .eyebrow { margin-bottom: var(--space-2); }
.tax-panel h3 { margin: 0 0 var(--space-2); font-size: 1.1rem; }
.tax-panel .panel-path {
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--ink-faint);
  margin-bottom: var(--space-3);
}
.tax-panel .panel-desc {
  font-family: var(--font-serif);
  font-size: 1rem;
  line-height: 1.55;
  color: var(--ink-soft);
  margin-bottom: var(--space-4);
}
.tax-panel ul.tax-refs {
  margin: 0; padding-left: 16px; font-size: 0.88rem; color: var(--ink-soft);
}
.tax-panel ul.tax-refs li { margin-bottom: 4px; }

.tax-tree-node circle {
  stroke-width: 2;
  cursor: pointer;
  transition: r 120ms ease, fill 120ms ease;
}
.tax-tree-node:hover circle { r: 7; }
.tax-tree-node.active circle { stroke: var(--crimson); stroke-width: 3; }
.tax-tree-node text {
  font-family: var(--font-sans);
  font-size: 12px;
  fill: var(--ink);
  cursor: pointer;
  pointer-events: none;
}
.tax-tree-link {
  fill: none;
  stroke: var(--ink-faint);
  stroke-width: 1.1;
  stroke-opacity: 0.6;
}

/* ---------- Footer ---------- */
.site-footer {
  margin-top: var(--space-8);
  background: #1d222c;
  color: #d6d4cc;
  padding: var(--space-8) 0 var(--space-6);
  font-size: 0.92rem;
}
.site-footer a { color: #f1e7d8; border-bottom-color: rgba(241, 231, 216, 0.35); }
.site-footer a:hover { color: #fff; border-bottom-color: #fff; }
.site-footer h4 {
  color: #fff;
  font-family: var(--font-serif);
  font-size: 1rem;
  margin-bottom: var(--space-3);
}
.footer-grid {
  display: grid;
  grid-template-columns: 1.2fr 1fr 1fr 1fr;
  gap: var(--space-6);
}
@media (max-width: 820px) { .footer-grid { grid-template-columns: 1fr 1fr; } }
.footer-grid ul { list-style: none; padding: 0; margin: 0; }
.footer-grid ul li { margin-bottom: 6px; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,0.08);
  margin-top: var(--space-6);
  padding-top: var(--space-4);
  color: #8f8b7e;
  font-size: 0.82rem;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: var(--space-3);
}

/* ---------- Utilities ---------- */
.muted { color: var(--ink-mute); }
.faint { color: var(--ink-faint); }
.center { text-align: center; }
.mono  { font-family: var(--font-mono); }
.serif { font-family: var(--font-serif); }
.right { text-align: right; }
.hidden { display: none !important; }
.mt-0 { margin-top: 0; } .mt-1 { margin-top: var(--space-1); }
.mt-2 { margin-top: var(--space-2); } .mt-3 { margin-top: var(--space-3); }
.mt-4 { margin-top: var(--space-4); } .mt-5 { margin-top: var(--space-5); }
.mt-6 { margin-top: var(--space-6); } .mt-7 { margin-top: var(--space-7); }
.mb-0 { margin-bottom: 0; } .mb-4 { margin-bottom: var(--space-4); }
.mb-5 { margin-bottom: var(--space-5); } .mb-6 { margin-bottom: var(--space-6); }
.only-desktop { }
@media (max-width: 720px) { .only-desktop { display: none; } }

/* ---------- Page-specific overrides ---------- */
.page-badge {
  display: inline-block;
  font-family: var(--font-sans);
  font-size: 0.72rem;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink-faint);
  margin-bottom: var(--space-3);
}
.section-header {
  border-left: 3px solid var(--crimson);
  padding-left: var(--space-4);
  margin-bottom: var(--space-6);
}
.section-header h2 { margin: 0; }
.section-header p { margin: var(--space-2) 0 0; color: var(--ink-mute); font-size: 0.95rem; max-width: 60ch; }

.pull {
  font-family: var(--font-serif);
  font-size: 1.25rem;
  line-height: 1.45;
  color: var(--crimson);
  border-left: 3px solid var(--crimson);
  padding: var(--space-3) var(--space-5);
  margin: var(--space-6) 0;
  max-width: 52ch;
  font-style: italic;
}

/* Definition list for terms/glossary */
dl.defs { margin: 0; }
dl.defs dt {
  font-family: var(--font-serif);
  font-weight: 600;
  color: var(--ink);
  font-size: 1.02rem;
  margin-top: var(--space-4);
}
dl.defs dd {
  margin: 2px 0 0;
  color: var(--ink-soft);
  font-size: 0.96rem;
  line-height: 1.55;
}

/* Challenge matrix */
.chal-matrix {
  display: grid;
  grid-template-columns: repeat(5, 1fr);
  gap: 2px;
  background: var(--rule);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  overflow: hidden;
}
@media (max-width: 980px) { .chal-matrix { grid-template-columns: repeat(2, 1fr); } }
@media (max-width: 560px) { .chal-matrix { grid-template-columns: 1fr; } }
.chal-cell {
  background: var(--panel);
  padding: var(--space-5);
  display: flex;
  flex-direction: column;
  min-height: 260px;
  position: relative;
  transition: background 120ms ease;
  cursor: pointer;
}
.chal-cell:hover { background: var(--paper-warm); }
.chal-cell.active { background: var(--ochre-tint); }
.chal-cell h4 { margin-top: 0; color: var(--ochre); font-size: 1.02rem; }
.chal-cell p { font-size: 0.88rem; color: var(--ink-mute); margin: 0 0 var(--space-3); }
.chal-cell ul { margin: 0; padding-left: 16px; font-size: 0.84rem; }
.chal-cell ul li { margin-bottom: 4px; color: var(--ink-soft); }

/* BibTeX box */
.bib-box {
  position: relative;
  background: #272b36;
  color: #e3e1d7;
  padding: var(--space-5);
  border-radius: var(--radius-md);
  font-family: var(--font-mono);
  font-size: 0.82rem;
  line-height: 1.55;
  overflow: auto;
}
.bib-copy {
  position: absolute;
  top: 10px;
  right: 10px;
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.14);
  color: #e3e1d7;
  padding: 4px 10px;
  border-radius: var(--radius-xs);
  font-family: var(--font-sans);
  font-size: 0.78rem;
  cursor: pointer;
  transition: background 140ms ease;
}
.bib-copy:hover { background: rgba(255,255,255,0.16); }
.bib-copy.copied { background: #2f6b3d; border-color: #2f6b3d; }

/* Taxonomy tree nodes — color by family */
.tax-tree-node.is-root circle  { fill: var(--crimson-tint); stroke: var(--crimson); }
.tax-tree-node.fam-if circle   { fill: var(--sage-tint); stroke: var(--sage); }
.tax-tree-node.fam-ce circle   { fill: var(--terra-tint); stroke: var(--terra); }
.tax-tree-node.fam-leaf circle { fill: #fff; stroke: var(--ink-mute); }

/* Pill list used under headings */
.pill-row {
  display: flex; flex-wrap: wrap; gap: 6px;
  margin: var(--space-2) 0 var(--space-5);
}

/* "Anchor link" decoration */
.anchor-chip {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 0.82rem;
  color: var(--ink-mute);
  background: var(--paper-warm);
  padding: 4px 10px;
  border-radius: 999px;
  border: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
}
.anchor-chip:hover { color: var(--crimson); border-color: var(--crimson); background: var(--crimson-tint); }

/* Hero figure (paper preview frame) */
.paper-frame {
  background: var(--panel);
  border: 1px solid var(--rule);
  border-radius: var(--radius-md);
  padding: var(--space-3);
  box-shadow: var(--shadow-lg);
  position: relative;
  transform: rotate(-1.2deg);
}
.paper-frame::before {
  content: ""; position: absolute; top: -8px; left: 16px; right: 16px;
  height: 16px; background: var(--paper-warm);
  border-radius: 3px 3px 0 0;
  border: 1px solid var(--rule);
  border-bottom: none;
  z-index: -1;
  transform: rotate(0.5deg);
}
.paper-frame-inner {
  border: 1px solid var(--rule);
  padding: var(--space-4) var(--space-5);
  min-height: 280px;
  background:
    repeating-linear-gradient(0deg, transparent, transparent 14px, #f3eee1 14px, #f3eee1 15px);
  font-family: var(--font-serif);
  color: var(--ink-mute);
  border-radius: var(--radius-xs);
}
.paper-frame h3 {
  text-align: center;
  font-size: 1.15rem;
  margin: 0 0 var(--space-3);
  color: var(--ink);
}
.paper-frame .paper-meta {
  text-align: center;
  font-size: 0.8rem;
  color: var(--ink-faint);
  margin-bottom: var(--space-3);
}

/* Print-ish */
@media print {
  .site-header, .site-footer, .nav-toggle { display: none; }
  body { background: #fff; }
}