:root {
  color-scheme: light dark;
  --fg: #1f2328;
  --bg: #ffffff;
  --muted: #59636e;
  --accent: #0969da;
  --border: #d1d9e0;
}

@media (prefers-color-scheme: dark) {
  :root {
    --fg: #f0f6fc;
    --bg: #0d1117;
    --muted: #9198a1;
    --accent: #4493f8;
    --border: #3d444d;
  }
}

* {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  padding: 2.5rem 1.25rem;
  font-family: system-ui, -apple-system, "Segoe UI", "Noto Sans JP", sans-serif;
  line-height: 1.7;
  color: var(--fg);
  background: var(--bg);
}

header,
main,
footer {
  max-width: 42rem;
  margin-inline: auto;
}

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

.tagline {
  margin: 0.25rem 0 2rem;
  font-size: 0.95rem;
  color: var(--muted);
}

h2 {
  margin: 2.25rem 0 0.75rem;
  padding-bottom: 0.35rem;
  font-size: 1.15rem;
  border-bottom: 1px solid var(--border);
}

p {
  margin: 0.5rem 0;
}

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

a:hover {
  text-decoration: underline;
}

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.links {
  margin: 0;
  padding: 0;
  list-style: none;
}

.links li {
  margin: 0.35rem 0;
}

footer {
  margin-top: 3rem;
  font-size: 0.875rem;
  color: var(--muted);
}