:root {
  --ink: #132033;
  --muted: #536273;
  --accent: #9b4d2f;
  --accent-soft: #d8895f;
  --paper: #fffaf2;
  --paper-2: #f4ecdf;
  --panel: rgba(255, 250, 242, 0.86);
  --line: rgba(19, 32, 51, 0.12);
  --shadow: 0 18px 48px rgba(26, 39, 58, 0.12);
  --radius: 20px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    radial-gradient(circle at top left, rgba(216, 137, 95, 0.22), transparent 28%),
    radial-gradient(circle at top right, rgba(40, 104, 123, 0.18), transparent 24%),
    linear-gradient(180deg, #fcf7ef 0%, #f2eadf 100%);
  font-family: "Avenir Next", "Segoe UI", "Helvetica Neue", sans-serif;
  line-height: 1.65;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

code,
pre {
  font-family: "JetBrains Mono", "Cascadia Code", "SFMono-Regular", monospace;
}

.site-shell {
  min-height: 100vh;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  backdrop-filter: blur(14px);
  background: rgba(252, 247, 239, 0.85);
  border-bottom: 1px solid var(--line);
}

.site-header-inner,
.content,
.site-footer-inner {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
}

.site-header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 14px 0;
}

.brand {
  display: flex;
  align-items: center;
  gap: 14px;
  color: var(--ink);
}

.brand-mark {
  width: 42px;
  height: 42px;
  display: grid;
  place-items: center;
  border-radius: 14px;
  background: linear-gradient(135deg, #17324e, #9b4d2f);
  color: white;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.brand-copy strong,
h1,
h2,
h3 {
  font-family: "Iowan Old Style", "Palatino Linotype", "Book Antiqua", Georgia, serif;
}

.brand-copy small {
  display: block;
  color: var(--muted);
}

.nav {
  display: flex;
  gap: 14px;
  flex-wrap: wrap;
}

.nav a {
  padding: 8px 12px;
  border-radius: 999px;
  color: var(--muted);
}

.nav a.active,
.nav a:hover {
  background: rgba(155, 77, 47, 0.1);
  color: var(--ink);
  text-decoration: none;
}

.hero {
  padding: 68px 0 28px;
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.45fr 0.95fr;
  gap: 26px;
}

.hero-card,
.panel,
.metric-card,
.note-card,
.feature-card,
.figure-card,
.callout,
.table-wrap {
  background: var(--panel);
  border: 1px solid rgba(255, 255, 255, 0.5);
  box-shadow: var(--shadow);
  border-radius: var(--radius);
}

.hero-card,
.panel,
.callout,
.figure-card,
.table-wrap {
  padding: 26px;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 12px;
  border-radius: 999px;
  background: rgba(23, 50, 78, 0.08);
  color: var(--accent);
  font-size: 0.92rem;
  font-weight: 600;
  letter-spacing: 0.02em;
}

h1 {
  font-size: clamp(2.3rem, 5vw, 4rem);
  line-height: 1.06;
  margin: 18px 0;
}

h2 {
  font-size: clamp(1.6rem, 3vw, 2.3rem);
  margin: 0 0 18px;
}

h3 {
  font-size: 1.2rem;
  margin: 0 0 12px;
}

.lead {
  font-size: 1.12rem;
  color: var(--muted);
  max-width: 60ch;
}

.equation-band {
  margin-top: 24px;
  padding: 18px 20px;
  border-radius: 18px;
  background: linear-gradient(135deg, rgba(19, 32, 51, 0.92), rgba(29, 68, 87, 0.9));
  color: white;
}

.equation-band code {
  font-size: clamp(1rem, 2vw, 1.25rem);
}

.hero-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  margin-top: 22px;
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 18px;
  border-radius: 999px;
  background: var(--ink);
  color: white;
  font-weight: 600;
}

.button.secondary {
  background: rgba(19, 32, 51, 0.08);
  color: var(--ink);
}

.button:hover {
  text-decoration: none;
}

.metric-grid,
.feature-grid,
.two-column,
.figure-grid,
.card-grid {
  display: grid;
  gap: 18px;
}

.metric-grid,
.feature-grid,
.card-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.metric-card,
.note-card,
.feature-card {
  padding: 20px;
}

.metric-card strong {
  display: block;
  font-size: 2rem;
  font-family: "Iowan Old Style", "Palatino Linotype", serif;
}

.metric-card span,
.note-card p,
.feature-card p,
.muted {
  color: var(--muted);
}

.content {
  padding: 12px 0 70px;
}

.section {
  margin-top: 44px;
}

.two-column {
  grid-template-columns: 1.1fr 0.9fr;
}

.formula-block,
.code-block {
  padding: 18px;
  border-radius: 18px;
  background: #fffdf9;
  border: 1px solid var(--line);
  overflow-x: auto;
}

.formula-block {
  white-space: pre-wrap;
}

.figure-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.figure-card img {
  width: 100%;
  display: block;
  border-radius: 14px;
  border: 1px solid var(--line);
  background: white;
}

.caption {
  margin-top: 12px;
  color: var(--muted);
  font-size: 0.95rem;
}

table {
  width: 100%;
  border-collapse: collapse;
}

th,
td {
  padding: 12px 14px;
  border-bottom: 1px solid var(--line);
  text-align: left;
}

th {
  color: var(--muted);
  font-weight: 700;
}

.site-footer {
  border-top: 1px solid var(--line);
  padding: 26px 0 44px;
}

.site-footer-inner {
  color: var(--muted);
  display: flex;
  justify-content: space-between;
  gap: 16px;
  flex-wrap: wrap;
}

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

ul.clean li + li {
  margin-top: 10px;
}

@media (max-width: 900px) {
  .hero-grid,
  .two-column,
  .figure-grid,
  .metric-grid,
  .feature-grid,
  .card-grid {
    grid-template-columns: 1fr;
  }

  .site-header-inner {
    align-items: flex-start;
    flex-direction: column;
  }
}