:root {
  --navy: #0d2340;
  --gold: #b8922a;
  --gold-lt: #d4ac50;
  --ivory: #f9f6ef;
  --parch: #ede8dc;
  --ink: #1c1a16;
  --ink-s: #6b6760;
  --rule: #d5cfc3;
  --ok: #2f7e5e;
  --warn: #9b2335;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  font-family: "Jost", sans-serif;
  font-weight: 300;
  font-size: 15px;
  line-height: 1.82;
  background:
    radial-gradient(circle at 2% 2%, rgba(184,146,42,.16) 0%, transparent 30%),
    radial-gradient(circle at 98% 0%, rgba(13,35,64,.1) 0%, transparent 28%),
    var(--ivory);
  color: var(--ink);
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 2rem;
  background: rgba(13, 35, 64, 0.93);
  border-bottom: 2px solid var(--gold);
  backdrop-filter: blur(8px);
  box-shadow: 0 8px 24px rgba(13, 35, 64, 0.22);
}

.logo {
  font-family: "JetBrains Mono", monospace;
  font-size: 1.02rem;
  color: #fff;
  text-decoration: none;
}

.logo span { color: var(--gold); }

.badge {
  color: var(--gold-lt);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.hero {
  background: linear-gradient(160deg, #0d2340 0%, #132f57 62%, #0d2340 100%);
  color: #fff;
  text-align: center;
  padding: 4.2rem 1rem 3.4rem;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background:
    radial-gradient(ellipse 60% 80% at 52% 120%, rgba(184,146,42,.2) 0%, transparent 72%),
    repeating-linear-gradient(-18deg, rgba(255,255,255,.03) 0 2px, transparent 2px 18px);
  pointer-events: none;
}

.hero-inner {
  position: relative;
  max-width: 900px;
  margin: 0 auto;
}

.kicker {
  margin: 0 0 0.9rem;
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--gold);
  font-weight: 600;
}

.hero h1 {
  margin: 0;
  font-family: "Cormorant Garamond", serif;
  font-size: clamp(2.1rem, 5vw, 3.7rem);
  line-height: 1.13;
  font-weight: 600;
}

.hero h1 em { color: var(--gold); font-style: normal; }

.hero p {
  margin: 0.9rem auto 0;
  max-width: 64ch;
  color: rgba(255,255,255,.74);
}

.container {
  max-width: 1040px;
  margin: 0 auto;
  padding: 0 1rem 4rem;
}

.section-title {
  margin: 2rem 0 0.5rem;
  display: flex;
  align-items: baseline;
  gap: 0.9rem;
}

.section-title h2 {
  margin: 0;
  font-family: "Cormorant Garamond", serif;
  font-size: 1.95rem;
  color: var(--navy);
}

.section-label {
  color: var(--gold);
  font-size: 11px;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.rule-gold {
  height: 3px;
  background: linear-gradient(90deg, var(--gold) 0%, transparent 100%);
  margin-bottom: 1rem;
}

.card {
  background: #fff;
  border: 1px solid var(--rule);
  border-radius: 12px;
  padding: 1rem 1.1rem;
  margin: 0.9rem 0;
  box-shadow: 0 8px 24px rgba(14, 24, 40, 0.06);
  transition: transform 180ms ease, box-shadow 180ms ease, border-color 180ms ease;
}

.card:hover {
  transform: translateY(-2px);
  box-shadow: 0 14px 32px rgba(14, 24, 40, 0.12);
  border-color: #cbb67b;
}

.card h3 {
  margin: 0 0 0.4rem;
  font-family: "Cormorant Garamond", serif;
  font-size: 1.32rem;
  color: var(--navy);
}

.card p { margin: 0.45rem 0; }

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.9rem;
}

.tag {
  display: inline-block;
  font-size: 10px;
  font-weight: 600;
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--ink-s);
  margin-bottom: 0.3rem;
}

pre {
  margin: 0.75rem 0;
  padding: 0.85rem 0.95rem;
  border-radius: 9px;
  background: #1b1f27;
  color: #e6edf8;
  overflow-x: auto;
  font-size: 0.8rem;
  line-height: 1.58;
}

code {
  font-family: "JetBrains Mono", monospace;
  font-size: 0.8rem;
}

:not(pre) > code {
  background: var(--parch);
  color: var(--navy);
  border-radius: 4px;
  padding: 0.1em 0.38em;
}

ul { margin: 0.5rem 0 0.3rem; padding-left: 1.15rem; }
li { margin: 0.22rem 0; }

.callout {
  border-left: 3px solid;
  border-radius: 0 8px 8px 0;
  padding: 0.6rem 0.9rem;
  margin: 0.8rem 0;
  background: #fff;
}

.callout.tip { border-left-color: var(--ok); }
.callout.warn { border-left-color: var(--warn); }
.callout.note { border-left-color: var(--gold); }

.lesson-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 1rem 0;
}

.lesson-nav a {
  text-decoration: none;
  color: var(--navy);
  border: 1px solid var(--rule);
  background: #fff;
  padding: 0.38rem 0.64rem;
  border-radius: 8px;
  font-size: 0.86rem;
  transition: background-color 160ms ease, color 160ms ease, border-color 160ms ease;
}

.lesson-nav a:hover {
  border-color: var(--gold);
  background: #fcf8ef;
}

.next-prev {
  margin-top: 1.1rem;
  padding-top: 0.8rem;
  border-top: 1px solid var(--rule);
  display: flex;
  justify-content: space-between;
  gap: 0.6rem;
}

.next-prev a {
  text-decoration: none;
  font-size: 0.9rem;
  color: var(--navy);
  font-weight: 400;
}

.next-prev a:hover { color: var(--gold); }

details {
  border: 1px dashed var(--rule);
  border-radius: 8px;
  padding: 0.5rem 0.7rem;
  margin-top: 0.8rem;
  background: #fff;
}

summary {
  cursor: pointer;
  color: var(--navy);
  font-weight: 600;
}

footer {
  margin-top: 2rem;
  background: var(--navy);
  border-top: 2px solid var(--gold);
  text-align: center;
  padding: 1.5rem;
  color: rgba(255,255,255,.55);
  font-size: 0.85rem;
}

/* Responsive Design */
@media (max-width: 768px) {
  .topbar {
    height: auto;
    flex-direction: column;
    gap: 0.35rem;
    padding: 0.8rem 1rem;
    text-align: center;
  }

  .hero-inner {
    text-align: center;
    padding: 0.2rem 0.4rem;
  }

  .grid-2 {
    grid-template-columns: 1fr;
    gap: 1rem;
  }

  .card {
    padding: 0.9rem 1rem;
  }

  .section-title {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.2rem;
  }
}

@media (max-width: 480px) {
  body {
    font-size: 14px;
  }

  .topbar {
    padding: 0.5rem;
  }

  .hero-inner {
    padding: 0;
  }

  .hero {
    padding: 3.3rem 0.75rem 2.6rem;
  }

  .lesson-nav {
    gap: 0.35rem;
  }

  .lesson-nav a {
    font-size: 0.82rem;
    padding: 0.34rem 0.56rem;
  }
}