:root {
  --bg: #f3f5f9;
  --surface: #ffffff;
  --ink: #16202b;
  --muted: #4f5b67;
  --brand: #0f766e;
  --line: #d8e0ea;
  --code: #0a1631;
}

* {
  box-sizing: border-box;
}

html,
body {
  margin: 0;
  padding: 0;
  font-family: "Segoe UI", Arial, sans-serif;
  color: var(--ink);
  background: radial-gradient(circle at top right, #dff5ef 0%, var(--bg) 40%);
}

.hero {
  max-width: 1200px;
  margin: 28px auto 10px;
  padding: 0 16px;
}

.eyebrow {
  color: var(--brand);
  font-weight: 700;
  margin: 0 0 4px;
}

.hero h1 {
  margin: 0;
  font-size: 2rem;
}

.lead {
  margin: 10px 0 0;
  color: var(--muted);
}

.layout {
  max-width: 1200px;
  margin: 14px auto 30px;
  padding: 0 16px;
  display: grid;
  grid-template-columns: 260px 1fr;
  gap: 16px;
}

.toc {
  position: sticky;
  top: 16px;
  align-self: start;
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 12px;
}

.toc h2 {
  margin: 0 0 10px;
  font-size: 1rem;
}

.toc a {
  display: block;
  color: #24435a;
  text-decoration: none;
  padding: 6px 8px;
  border-radius: 8px;
  font-size: 0.92rem;
}

.toc a:hover {
  background: #edf8f6;
}

.content {
  display: grid;
  gap: 12px;
}

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 12px;
  padding: 16px;
}

.card h2 {
  margin: 0 0 10px;
}

.card p,
.card li {
  line-height: 1.5;
}

code {
  background: #edf2f8;
  border-radius: 4px;
  padding: 1px 4px;
}

.codebox {
  background: var(--code);
  border-radius: 10px;
  padding: 12px;
  margin: 8px 0;
  overflow: auto;
}

.codebox pre {
  margin: 0;
}

.codebox code {
  color: #c8f8e4;
  background: transparent;
  padding: 0;
}

@media (max-width: 980px) {
  .layout {
    grid-template-columns: 1fr;
  }

  .toc {
    position: static;
  }
}