:root {
  --bg: #ffffff;
  --fg: #1c1c1e;
  --muted: #6b6b70;
  --accent: #007aff;
  --border: #e5e5ea;
  --code-bg: #f5f5f7;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1c1c1e;
    --fg: #f2f2f7;
    --muted: #aeaeb2;
    --accent: #0a84ff;
    --border: #38383a;
    --code-bg: #2c2c2e;
  }
}

* {
  box-sizing: border-box;
}

html {
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  background: var(--bg);
  color: var(--fg);
  line-height: 1.6;
  margin: 0;
  padding: 2rem 1rem;
  max-width: 720px;
  margin-left: auto;
  margin-right: auto;
}

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

header h1 {
  margin: 0 0 0.25rem 0;
  font-size: 1.75rem;
}

header p {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

nav {
  margin-top: 0.75rem;
}

nav a {
  color: var(--accent);
  text-decoration: none;
  margin-right: 1rem;
  font-size: 0.95rem;
}

nav a:hover {
  text-decoration: underline;
}

h2 {
  margin-top: 2.5rem;
  font-size: 1.25rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.25rem;
}

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

a {
  color: var(--accent);
}

code {
  background: var(--code-bg);
  padding: 0.1rem 0.35rem;
  border-radius: 4px;
  font-family: "SF Mono", Menlo, Consolas, monospace;
  font-size: 0.9em;
}

ul, ol {
  padding-left: 1.5rem;
}

li {
  margin: 0.25rem 0;
}

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