:root {
  --bg: #0f172a;
  --panel: #111827;
  --panel-2: #1f2937;
  --text: #e5e7eb;
  --muted: #9ca3af;
  --accent: #60a5fa;
  --accent-2: #22c55e;
  --border: rgba(255,255,255,0.08);
  --code: #0b1220;
  --warning: #7c2d12;
  --note: #0c4a6e;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  font-family: Inter, Segoe UI, Roboto, Arial, sans-serif;
  background: linear-gradient(180deg, #020617 0%, #0f172a 100%);
  color: var(--text);
  line-height: 1.6;
}

.hero {
  padding: 48px 24px 28px;
  border-bottom: 1px solid var(--border);
  background: radial-gradient(circle at top left, rgba(96,165,250,.18), transparent 30%),
              radial-gradient(circle at top right, rgba(34,197,94,.12), transparent 24%);
}

.hero-inner, .layout {
  max-width: 1400px;
  margin: 0 auto;
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: .12em;
  color: var(--accent);
  font-size: .78rem;
  font-weight: 700;
}

h1, h2, h3, h4 {
  line-height: 1.2;
}

h1 {
  font-size: clamp(2rem, 5vw, 3.4rem);
  margin: 10px 0 14px;
}

.lead {
  font-size: 1.08rem;
  max-width: 980px;
  color: #dbeafe;
}

.hero-note {
  margin-top: 18px;
  padding: 14px 16px;
  background: rgba(255,255,255,.05);
  border: 1px solid var(--border);
  border-radius: 16px;
}

.keywords {
  color: var(--muted);
}

.layout {
  display: grid;
  grid-template-columns: 280px minmax(0, 1fr);
  gap: 24px;
  padding: 24px;
}

.sidebar {
  position: sticky;
  top: 18px;
  align-self: start;
}

.sidebar nav {
  background: rgba(17,24,39,.85);
  backdrop-filter: blur(10px);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 18px;
}

.sidebar h2 {
  font-size: 1rem;
  margin-top: 0;
}

.sidebar a {
  display: block;
  color: #cbd5e1;
  text-decoration: none;
  padding: 8px 10px;
  border-radius: 10px;
  margin-bottom: 4px;
}

.sidebar a:hover {
  background: rgba(96,165,250,.12);
  color: white;
}

.content {
  display: grid;
  gap: 18px;
}

.card {
  background: rgba(17,24,39,.9);
  border: 1px solid var(--border);
  border-radius: 22px;
  padding: 24px;
  box-shadow: 0 12px 40px rgba(0,0,0,.22);
}

.card.accent {
  border-color: rgba(96,165,250,.35);
  background: linear-gradient(180deg, rgba(30,41,59,.95), rgba(17,24,39,.95));
}

.grid-2 {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.note, .warning {
  padding: 14px 16px;
  border-radius: 14px;
  margin-top: 14px;
}

.note {
  background: rgba(12,74,110,.35);
  border: 1px solid rgba(56,189,248,.2);
}

.warning {
  background: rgba(124,45,18,.35);
  border: 1px solid rgba(251,146,60,.25);
}

pre {
  background: var(--code);
  border: 1px solid rgba(255,255,255,.08);
  border-radius: 16px;
  padding: 16px;
  overflow: auto;
  white-space: pre;
}

code, kbd {
  font-family: "Cascadia Code", "Fira Code", Consolas, monospace;
}

kbd {
  background: #0b1220;
  border: 1px solid rgba(255,255,255,.15);
  border-bottom-width: 3px;
  border-radius: 8px;
  padding: 2px 6px;
  font-size: .92em;
}

ul, ol {
  padding-left: 22px;
}

.glossary {
  display: grid;
  grid-template-columns: 280px 1fr;
  gap: 10px 16px;
}

.glossary dt {
  font-weight: 700;
  color: #bfdbfe;
}

.glossary dd {
  margin: 0;
  color: #e5e7eb;
}

.quiz-item {
  padding: 16px;
  border: 1px solid var(--border);
  border-radius: 16px;
  background: rgba(255,255,255,.03);
  margin-bottom: 14px;
}

p, li, dd {
  overflow-wrap: anywhere;
}

@media (max-width: 1024px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .sidebar {
    position: static;
  }
}

@media (max-width: 720px) {
  .grid-2, .glossary {
    grid-template-columns: 1fr;
  }

  .card, .sidebar nav {
    padding: 18px;
  }

  .layout, .hero {
    padding-left: 14px;
    padding-right: 14px;
  }
}