:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --fg: #1a1a1a;
  --muted: #666666;
  --accent: #5865f2;
  --border: #e3e3e3;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16171a;
    --fg: #e6e6e6;
    --muted: #9a9a9a;
    --border: #2c2d31;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Kaku Gothic ProN", "Noto Sans JP", sans-serif;
  line-height: 1.7;
}

header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1rem 1.5rem;
  border-bottom: 1px solid var(--border);
  max-width: 760px;
  margin: 0 auto;
}

header a.home {
  color: var(--fg);
  text-decoration: none;
  font-weight: 600;
}

nav.lang-switch {
  display: flex;
  gap: 0.5rem;
}

nav.lang-switch button {
  border: 1px solid var(--border);
  background: transparent;
  color: var(--fg);
  padding: 0.3rem 0.7rem;
  border-radius: 6px;
  cursor: pointer;
  font-size: 0.85rem;
}

nav.lang-switch button[aria-pressed="true"] {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
}

main {
  max-width: 760px;
  margin: 0 auto;
  padding: 2rem 1.5rem 4rem;
}

h1 {
  font-size: 1.6rem;
  margin-bottom: 0.25rem;
}

.updated {
  color: var(--muted);
  font-size: 0.85rem;
  margin-bottom: 2rem;
}

h2 {
  font-size: 1.1rem;
  margin-top: 2rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.3rem;
}

ul {
  padding-left: 1.3rem;
}

.placeholder {
  color: var(--accent);
  font-weight: 600;
}

[data-lang] {
  display: none;
}

[data-lang].active {
  display: block;
}

footer {
  max-width: 760px;
  margin: 0 auto;
  padding: 1.5rem;
  color: var(--muted);
  font-size: 0.8rem;
  border-top: 1px solid var(--border);
}

footer a {
  color: var(--muted);
}

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

.index-links li {
  margin: 0.8rem 0;
}

.index-links a {
  color: var(--accent);
  font-size: 1.05rem;
  text-decoration: none;
}

.index-links a:hover {
  text-decoration: underline;
}