:root {
  --bg: #FAFAF6;
  --bg-tint: #F5F2EA;
  --paper: #FFFFFF;
  --cream: #FFFBF5;
  --ink: #1A1D21;
  --ink-soft: #3D4451;
  --muted: #6B7280;
  --rule: #D8DAD3;
  --rule-soft: #E8E9E2;
  --grid: #C8CAC0;
  --navy: #1B2A4E;
  --navy-light: #3D5A80;
  --teal: #0E7C7B;
  --teal-soft: #E8F1F0;
  --amber: #C99B2D;
  --serif: 'Source Serif 4', Georgia, 'Times New Roman', serif;
  --sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --mono: 'JetBrains Mono', 'SF Mono', Menlo, monospace;
  --column: 760px;
  --column-wide: 1080px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html {
  scroll-behavior: smooth;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  background: var(--bg);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.7;
  font-weight: 400;
  position: relative;
  overflow-x: hidden;
}

.bg-grid {
  position: fixed;
  inset: 0;
  pointer-events: none;
  z-index: 0;
  opacity: 0.4;
  background-image:
    linear-gradient(to right, var(--grid) 1px, transparent 1px),
    linear-gradient(to bottom, var(--grid) 1px, transparent 1px);
  background-size: 32px 32px;
  mask-image: radial-gradient(ellipse 100% 80% at 50% 30%, black 0%, transparent 90%);
  -webkit-mask-image: radial-gradient(ellipse 100% 80% at 50% 30%, black 0%, transparent 90%);
}

.topbar, main, footer { position: relative; z-index: 1; }

/* Topbar */
.topbar {
  border-bottom: 1px solid var(--rule);
  background: rgba(250, 250, 246, 0.85);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  position: sticky;
  top: 0;
  z-index: 100;
}

.topbar-inner {
  max-width: var(--column-wide);
  margin: 0 auto;
  padding: 18px 32px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
}

.topbar-brand {
  display: flex;
  align-items: center;
  gap: 14px;
  text-decoration: none;
}

.topbar-mark { width: 22px; height: 22px; flex-shrink: 0; }
.topbar-mark svg { width: 100%; height: 100%; display: block; }

.topbar-name {
  font-family: var(--mono);
  font-size: 14px;
  font-weight: 500;
  color: var(--navy);
  letter-spacing: 0.12em;
}

.topbar-nav {
  display: flex;
  align-items: center;
  gap: 26px;
  margin-left: auto;
}

.topbar-nav a {
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 500;
  letter-spacing: 0.02em;
  color: var(--ink-soft);
  text-decoration: none;
  transition: color 160ms ease;
}

.topbar-nav a:hover { color: var(--navy); }
.topbar-nav a.is-current { color: var(--navy); font-weight: 600; }

.topbar-actions { display: flex; align-items: center; gap: 14px; }

.btn-login {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 18px;
  font-family: var(--sans);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--paper);
  background: var(--navy);
  border: 1px solid var(--navy);
  border-radius: 4px;
  text-decoration: none;
  transition: background 160ms ease, transform 160ms ease;
}

.btn-login:hover { background: var(--navy-light); border-color: var(--navy-light); }
.btn-login:active { transform: translateY(1px); }

@media (max-width: 720px) {
  .topbar-inner { padding: 14px 20px; gap: 12px; }
  .topbar-nav { gap: 14px; }
  .topbar-nav a { font-size: 12px; }
  .topbar-actions .btn-login { padding: 7px 12px; font-size: 12px; }
}

/* Layout */
.column {
  max-width: var(--column);
  margin: 0 auto;
  padding: 0 32px;
}

main.doc { padding: 70px 0 110px; }

@media (max-width: 720px) {
  main.doc { padding: 40px 0 80px; }
  .column { padding: 0 20px; }
}

/* Page header */
.page-eyebrow {
  display: inline-block;
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--teal);
  background: var(--teal-soft);
  padding: 6px 12px;
  border-radius: 2px;
  margin-bottom: 22px;
}

.page-title {
  font-family: var(--serif);
  font-size: clamp(38px, 5vw, 56px);
  font-weight: 700;
  line-height: 1.08;
  color: var(--navy);
  margin-bottom: 18px;
  letter-spacing: -0.01em;
}

.page-title em {
  font-style: italic;
  color: var(--teal);
}

.page-lede {
  font-family: var(--serif);
  font-size: 19px;
  line-height: 1.55;
  color: var(--ink-soft);
  margin-bottom: 50px;
  max-width: 640px;
}

/* Table of contents */
.toc {
  background: var(--paper);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--teal);
  padding: 22px 26px;
  margin-bottom: 64px;
  border-radius: 2px;
}

.toc h2 {
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 14px;
}

.toc ol {
  list-style: none;
  counter-reset: toc;
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(240px, 1fr));
  gap: 8px 28px;
}

.toc li {
  counter-increment: toc;
  position: relative;
  padding-left: 26px;
  font-size: 14.5px;
}

.toc li::before {
  content: counter(toc, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 1px;
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 500;
  color: var(--teal);
  letter-spacing: 0.05em;
}

.toc a {
  color: var(--ink-soft);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 140ms ease, border-color 140ms ease;
}

.toc a:hover { color: var(--navy); border-bottom-color: var(--rule); }

/* Sections */
.section {
  padding-top: 56px;
  margin-top: 56px;
  border-top: 1px solid var(--rule-soft);
  scroll-margin-top: 90px;
}

.section:first-of-type { border-top: none; padding-top: 0; margin-top: 0; }

.section h2 {
  font-family: var(--serif);
  font-size: 30px;
  font-weight: 700;
  color: var(--navy);
  line-height: 1.2;
  margin-bottom: 8px;
  letter-spacing: -0.005em;
}

.section h3 {
  font-family: var(--sans);
  font-size: 18px;
  font-weight: 600;
  color: var(--navy);
  margin-top: 32px;
  margin-bottom: 10px;
}

.section-num {
  display: block;
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 500;
  letter-spacing: 0.16em;
  color: var(--teal);
  margin-bottom: 10px;
}

.section p { margin-bottom: 18px; color: var(--ink-soft); }
.section p strong { color: var(--ink); font-weight: 600; }

.section ul, .section ol {
  margin: 14px 0 22px 22px;
  color: var(--ink-soft);
}

.section ul li, .section ol li { margin-bottom: 8px; }

.section a {
  color: var(--teal);
  text-decoration: none;
  border-bottom: 1px solid var(--teal-soft);
}

.section a:hover { border-bottom-color: var(--teal); }

code, kbd {
  font-family: var(--mono);
  font-size: 0.88em;
  background: var(--bg-tint);
  padding: 2px 6px;
  border-radius: 3px;
  color: var(--navy);
}

/* Callouts */
.callout {
  background: var(--cream);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--amber);
  padding: 18px 22px;
  margin: 22px 0;
  border-radius: 2px;
  font-size: 15.5px;
}

.callout--teal { border-left-color: var(--teal); }
.callout--navy { border-left-color: var(--navy); }

.callout-label {
  display: inline-block;
  font-family: var(--mono);
  font-size: 10.5px;
  font-weight: 600;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--amber);
  margin-bottom: 6px;
}

.callout--teal .callout-label { color: var(--teal); }
.callout--navy .callout-label { color: var(--navy); }

/* Step blocks for tutorial */
.step {
  display: grid;
  grid-template-columns: 60px 1fr;
  gap: 24px;
  padding: 28px 0;
  border-bottom: 1px dashed var(--rule);
}

.step:last-child { border-bottom: none; }

.step-num {
  font-family: var(--serif);
  font-size: 38px;
  font-weight: 700;
  font-style: italic;
  color: var(--teal);
  line-height: 1;
}

.step h3 {
  font-family: var(--serif);
  font-size: 22px;
  font-weight: 700;
  color: var(--navy);
  margin: 0 0 8px;
}

.step p { color: var(--ink-soft); margin-bottom: 12px; }

@media (max-width: 600px) {
  .step { grid-template-columns: 1fr; gap: 4px; }
  .step-num { font-size: 30px; margin-bottom: 4px; }
}

/* Glossary */
.glossary {
  background: var(--paper);
  border: 1px solid var(--rule);
  border-radius: 2px;
  padding: 0;
  overflow: hidden;
}

.glossary dt {
  font-family: var(--sans);
  font-weight: 600;
  font-size: 14.5px;
  color: var(--navy);
  padding: 16px 22px 4px;
}

.glossary dd {
  padding: 0 22px 16px;
  font-size: 15px;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--rule-soft);
}

.glossary dd:last-child { border-bottom: none; }

/* Footer */
.doc-footer {
  border-top: 1px solid var(--rule);
  padding: 50px 0 60px;
  margin-top: 80px;
  font-family: var(--serif);
  font-style: italic;
  font-size: 14px;
  color: var(--muted);
  text-align: center;
}

.doc-footer a { color: var(--teal); text-decoration: none; }
.doc-footer a:hover { text-decoration: underline; }