:root {
  --fg: #1a1a1a;
  --fg-muted: #555;
  --bg: #fafafa;
  --accent: #c0392b;
  --rule: #ddd;
  --max: 720px;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  padding: 0;
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic", "Helvetica Neue", Arial, sans-serif;
  font-size: 16px;
  line-height: 1.7;
  color: var(--fg);
  background: var(--bg);
}

header, main, footer {
  max-width: var(--max);
  margin: 0 auto;
  padding: 0 1.25rem;
}

header {
  padding-top: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 2rem;
}

h1 {
  font-size: 2rem;
  margin: 0 0 0.5rem 0;
  letter-spacing: 0.02em;
}

.tagline {
  margin: 0;
  color: var(--fg-muted);
  font-size: 1rem;
}

main section {
  margin-bottom: 2.5rem;
}

h2 {
  font-size: 1.25rem;
  margin: 0 0 0.75rem 0;
  border-left: 3px solid var(--accent);
  padding-left: 0.6rem;
}

h3 {
  font-size: 1.05rem;
  margin: 1.5rem 0 0.5rem 0;
}

p { margin: 0.5rem 0; }

ul, ol { padding-left: 1.5rem; }
li { margin: 0.25rem 0; }

dl { margin: 0.5rem 0; }
dt {
  font-weight: 600;
  margin-top: 0.5rem;
}
dd {
  margin: 0 0 0.25rem 0;
}

a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}
a:hover { opacity: 0.7; }

.muted {
  color: var(--fg-muted);
  font-size: 0.9rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 1rem 0;
  font-size: 0.9rem;
}
th, td {
  padding: 0.5rem;
  border: 1px solid var(--rule);
  text-align: left;
  vertical-align: top;
}
th { background: #f0f0f0; }

code {
  font-family: "SF Mono", Menlo, monospace;
  font-size: 0.9em;
  background: #efefef;
  padding: 0.1em 0.3em;
  border-radius: 3px;
}

footer {
  margin-top: 4rem;
  padding-top: 2rem;
  padding-bottom: 3rem;
  border-top: 1px solid var(--rule);
  color: var(--fg-muted);
  font-size: 0.85rem;
  text-align: center;
}

@media (max-width: 480px) {
  body { font-size: 15px; }
  h1 { font-size: 1.6rem; }
  h2 { font-size: 1.1rem; }
}