:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --text: #1a1a1a;
  --muted: #666666;
  --accent: #036cef;
  --border: #e5e5e5;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0d1117;
    --text: #e6edf3;
    --muted: #8b949e;
    --accent: #4493f8;
    --border: #30363d;
  }
}

* { box-sizing: border-box; }

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans",
    "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  margin: 0;
  padding: 2rem 1rem;
}

main {
  max-width: 720px;
  margin: 0 auto;
}

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

h1 {
  font-size: 1.6rem;
  margin: 0 0 0.5rem 0;
}

h2 {
  font-size: 1.2rem;
  margin-top: 2rem;
  border-left: 3px solid var(--accent);
  padding-left: 0.6rem;
}

h3 {
  font-size: 1rem;
  margin-top: 1.5rem;
}

.meta {
  color: var(--muted);
  font-size: 0.875rem;
  margin: 0;
}

.lang-switch {
  font-size: 0.875rem;
  color: var(--muted);
  text-align: right;
  margin-bottom: 1rem;
}

a {
  color: var(--accent);
  text-decoration: none;
}

a:active {
  text-decoration: underline;
}

ul {
  padding-left: 1.4rem;
}

li {
  margin-bottom: 0.4rem;
}

footer {
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.875rem;
  text-align: center;
}

code {
  background: var(--border);
  padding: 0.1em 0.4em;
  border-radius: 3px;
  font-size: 0.9em;
}