:root {
  --fg: #1a1a1a;
  --fg-muted: #555;
  --bg: #fafafa;
  --accent: #4f46e5;
  --border: #e5e5e5;
  --code-bg: #f0f0f0;
}

* { box-sizing: border-box; }

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

body {
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  font-size: 16px;
  line-height: 1.6;
  color: var(--fg);
  background: var(--bg);
  margin: 0;
  padding: 24px 16px 64px;
}

main {
  max-width: 760px;
  margin: 0 auto;
}

header.lang-switch {
  display: flex;
  justify-content: flex-end;
  gap: 12px;
  font-size: 14px;
  color: var(--fg-muted);
  margin-bottom: 24px;
}

header.lang-switch a {
  color: var(--accent);
  text-decoration: none;
}

header.lang-switch a.active {
  font-weight: 600;
  color: var(--fg);
  text-decoration: none;
  pointer-events: none;
}

h1 {
  font-size: 28px;
  margin: 0 0 8px;
  line-height: 1.25;
}

h2 {
  font-size: 20px;
  margin: 32px 0 8px;
  line-height: 1.3;
  border-top: 1px solid var(--border);
  padding-top: 24px;
}

h3 {
  font-size: 16px;
  margin: 20px 0 4px;
  color: var(--fg);
}

p, ul, ol {
  margin: 8px 0 12px;
}

ul, ol {
  padding-left: 24px;
}

li {
  margin: 4px 0;
}

a {
  color: var(--accent);
  text-decoration: underline;
}

code {
  font-family: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  font-size: 14px;
  background: var(--code-bg);
  padding: 1px 6px;
  border-radius: 3px;
}

.meta {
  color: var(--fg-muted);
  font-size: 14px;
  margin: 0 0 24px;
}

.callout {
  background: #fff;
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  padding: 12px 16px;
  border-radius: 4px;
  margin: 16px 0;
  font-size: 15px;
}

footer {
  margin-top: 48px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
  font-size: 14px;
  color: var(--fg-muted);
  text-align: center;
}

@media (prefers-color-scheme: dark) {
  :root {
    --fg: #e5e5e5;
    --fg-muted: #aaa;
    --bg: #121212;
    --accent: #818cf8;
    --border: #2a2a2a;
    --code-bg: #1e1e1e;
  }
  .callout { background: #1a1a1a; }
}