:root {
  color-scheme: dark;
  --bg: radial-gradient(circle at top, rgba(139, 92, 246, 0.18), transparent 38%),
    linear-gradient(180deg, #06070c 0%, #0a0d14 45%, #090b11 100%);
  --text: #ffffff;
  --soft: rgba(255, 255, 255, 0.72);
  --muted: rgba(255, 255, 255, 0.55);
  --panel: rgba(255, 255, 255, 0.04);
  --panel-strong: rgba(0, 0, 0, 0.35);
  --panel-border: rgba(255, 255, 255, 0.10);
  --chip-bg: rgba(255, 255, 255, 0.05);
  --table-head: rgba(255, 255, 255, 0.03);
  --surface-alt: rgba(0, 0, 0, 0.20);
  --shadow: 0 20px 60px rgba(0, 0, 0, 0.18);
  --violet: #c4b5fd;
  --violet-strong: #8b5cf6;
  --good-bg: rgba(16, 185, 129, 0.14);
  --good-border: rgba(16, 185, 129, 0.45);
  --warn-bg: rgba(245, 158, 11, 0.12);
  --warn-border: rgba(245, 158, 11, 0.40);
  --trap-bg: rgba(244, 63, 94, 0.12);
  --trap-border: rgba(244, 63, 94, 0.40);
  --emerald-text: #bbf7d0;
  --rose-text: #fecdd3;
}

body.light {
  color-scheme: light;
  --bg: radial-gradient(circle at top, rgba(168, 85, 247, 0.16), transparent 38%),
    linear-gradient(180deg, #f8fafc 0%, #eef2ff 42%, #f8fafc 100%);
  --text: #09090b;
  --soft: #52525b;
  --muted: #71717a;
  --panel: rgba(255, 255, 255, 0.80);
  --panel-strong: rgba(255, 255, 255, 0.75);
  --panel-border: #e4e4e7;
  --chip-bg: #f4f4f5;
  --table-head: #fafafa;
  --surface-alt: #fafafa;
  --shadow: 0 20px 60px rgba(0, 0, 0, 0.08);
  --violet: #7c3aed;
  --violet-strong: #8b5cf6;
  --emerald-text: #047857;
  --rose-text: #be123c;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-height: 100vh;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
}

a { color: inherit; text-decoration: none; }
button { font: inherit; }

.page {
  max-width: 1240px;
  margin: 0 auto;
  padding: 24px 20px 96px;
}

.sticky-bar {
  position: sticky;
  top: 16px;
  z-index: 30;
  border: 1px solid var(--panel-border);
  background: var(--panel-strong);
  border-radius: 24px;
  padding: 14px 16px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(20px);
}

.sticky-inner,
.hero-grid,
.framework-grid,
.example-grid,
.appendix-grid,
.stats-grid,
.overview-grid,
.theorem-grid,
.limits-grid,
.formula-grid,
.footer-signature,
.narrative-grid,
.flow-legend,
.open-grid,
.weighted-grid,
.card-grid {
  display: grid;
  gap: 16px;
}

.sticky-inner { grid-template-columns: 1fr; align-items: center; }
.brand-title { font-size: 0.95rem; font-weight: 700; letter-spacing: -0.04em; }
.brand-subtitle { font-size: 0.78rem; color: var(--soft); margin-top: 2px; }

.nav-list,
.control-list,
.chip-list,
.flow-legend,
.signature-badge {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
}

.nav-link,
.control-btn,
.chip {
  border: 1px solid var(--panel-border);
  border-radius: 999px;
  background: var(--chip-bg);
  color: var(--soft);
  padding: 8px 12px;
  font-size: 0.78rem;
  transition: background 0.18s ease, color 0.18s ease, border-color 0.18s ease, transform 0.18s ease;
}

.nav-link:hover,
.control-btn:hover,
.chip:hover {
  background: rgba(255, 255, 255, 0.10);
  color: var(--text);
  transform: translateY(-1px);
}

body.light .nav-link:hover,
body.light .control-btn:hover,
body.light .chip:hover {
  background: white;
}

.control-btn {
  cursor: pointer;
  color: var(--text);
  font-weight: 600;
}

.section {
  padding-top: 80px;
}

.hero-grid { grid-template-columns: 1fr; gap: 24px; padding-top: 48px; align-items: end; }
.hero-title {
  max-width: 900px;
  font-size: clamp(2.2rem, 6vw, 4.4rem);
  line-height: 0.98;
  letter-spacing: -0.06em;
  margin: 0;
  font-weight: 700;
}
.hero-body { max-width: 860px; margin-top: 20px; font-size: 1.04rem; line-height: 1.95; color: var(--soft); }

.panel {
  border: 1px solid var(--panel-border);
  background: var(--panel);
  border-radius: 32px;
  padding: 24px;
  box-shadow: var(--shadow);
  backdrop-filter: blur(10px);
}

.panel-title {
  font-size: 0.95rem;
  font-weight: 700;
  letter-spacing: -0.03em;
}

.panel-body,
.card-text,
.section-body,
.bullet-text,
.table-note,
.footer-text,
.note-text {
  color: var(--soft);
  line-height: 1.85;
}

.stats-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); margin-top: 20px; }
.mini-stat {
  border: 1px solid var(--panel-border);
  background: var(--surface-alt);
  border-radius: 20px;
  padding: 16px;
}
.mini-label {
  font-size: 0.68rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--violet);
  font-weight: 700;
}
.mini-value { margin-top: 8px; font-size: 0.92rem; font-weight: 600; }

.section-kicker {
  font-size: 0.72rem;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  font-weight: 700;
  color: var(--violet);
  margin-bottom: 12px;
}

.section-title {
  margin: 0;
  font-size: clamp(1.8rem, 4vw, 2.25rem);
  line-height: 1.1;
  letter-spacing: -0.04em;
}

.section-body { max-width: 760px; margin-top: 16px; font-size: 1rem; }
.overview-grid,
.theorem-grid,
.limits-grid,
.narrative-grid,
.open-grid { margin-top: 32px; }
.overview-grid,
.limits-grid { grid-template-columns: 1fr; }
.theorem-grid { grid-template-columns: 1fr; }
.narrative-grid { grid-template-columns: 1fr; }

.card,
.bullet-card,
.theorem-card,
.open-card {
  border: 1px solid var(--panel-border);
  background: var(--panel);
  border-radius: 24px;
  padding: 20px;
  backdrop-filter: blur(10px);
}

.framework-grid,
.example-grid,
.appendix-grid { grid-template-columns: 1fr; margin-top: 32px; }

.math-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  border-radius: 18px;
  border: 1px solid var(--panel-border);
  background: var(--surface-alt);
  padding: 14px 16px;
}
.math-wrap math { font-size: 1rem; }
@media (min-width: 640px) { .math-wrap math { font-size: 1.06rem; } }

.formula-grid { grid-template-columns: 1fr; margin-top: 32px; }
.formula-card {
  border: 1px solid var(--panel-border);
  background: var(--panel);
  border-radius: 28px;
  padding: 20px;
  box-shadow: var(--shadow);
}
.formula-title { font-size: 0.92rem; font-weight: 700; letter-spacing: -0.02em; margin-bottom: 12px; }
.formula-note { margin-top: 12px; font-size: 0.92rem; color: var(--soft); line-height: 1.7; }

.table-wrap {
  margin-top: 16px;
  overflow-x: auto;
  border-radius: 18px;
  border: 1px solid var(--panel-border);
}

table {
  width: 100%;
  min-width: 420px;
  border-collapse: collapse;
  font-size: 0.94rem;
}

thead { background: var(--table-head); color: var(--muted); }
th, td {
  text-align: left;
  padding: 12px 14px;
  border-top: 1px solid var(--panel-border);
}
thead th { border-top: none; font-weight: 600; }

.diagram-box {
  border: 1px solid var(--panel-border);
  background: var(--panel);
  border-radius: 32px;
  padding: 20px;
  box-shadow: var(--shadow);
}
.diagram-subtitle { font-size: 0.92rem; color: var(--soft); line-height: 1.7; margin: 8px 0 20px; }
.diagram-svg { width: 100%; height: auto; display: block; overflow: visible; }
.legend-dot { width: 10px; height: 10px; border-radius: 999px; display: inline-block; }
.dot-good { background: rgba(16,185,129,0.9); }
.dot-warn { background: rgba(245,158,11,0.9); }
.dot-trap { background: rgba(244,63,94,0.9); }
.legend-item { display: flex; align-items: center; gap: 8px; font-size: 0.78rem; color: var(--soft); }

.accent-box {
  border-radius: 18px;
  padding: 16px;
}
.accent-green { border: 1px solid rgba(16,185,129,0.2); background: rgba(16,185,129,0.05); }
.accent-red { border: 1px solid rgba(244,63,94,0.2); background: rgba(244,63,94,0.05); }
.accent-title-green { color: var(--emerald-text); font-size: 0.92rem; font-weight: 600; }
.accent-title-red { color: var(--rose-text); font-size: 0.92rem; font-weight: 600; }

.footer-block { margin-top: 80px; }
.signature-badge {
  margin-top: 18px;
  display: inline-flex;
  border: 1px solid rgba(168, 85, 247, 0.20);
  background: rgba(168, 85, 247, 0.10);
  border-radius: 999px;
  padding: 10px 14px;
}
.signature-label {
  font-size: 0.72rem;
  letter-spacing: 0.22em;
  text-transform: uppercase;
  color: var(--violet);
  font-weight: 700;
}
.signature-name {
  font-size: 0.92rem;
  letter-spacing: 0.18em;
  font-weight: 700;
}

@media (min-width: 768px) {
  .sticky-inner { grid-template-columns: auto 1fr auto; gap: 20px; }
  .overview-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .theorem-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .limits-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .narrative-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .open-grid { grid-template-columns: 1fr; }
  .formula-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}

@media (min-width: 1100px) {
  .hero-grid { grid-template-columns: 1.1fr 0.9fr; }
  .framework-grid { grid-template-columns: 0.95fr 1.05fr; }
  .example-grid { grid-template-columns: 1.1fr 0.9fr; }
  .appendix-grid { grid-template-columns: 1.05fr 0.95fr; }
  .theorem-grid { grid-template-columns: repeat(4, minmax(0, 1fr)); }
  .limits-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}