:root {
  --bg: #ffffff;
  --surface: #f7f7f8;
  --text: #1d1d1f;
  --text-muted: rgba(0, 0, 0, 0.6);
  --border: rgba(0, 0, 0, 0.1);
  --accent: #429ff0;
  --accent-hover: #2b8ee0;
  --max-width: 720px;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1c1c1e;
    --surface: #2a2a2c;
    --text: #f2f2f5;
    --text-muted: rgba(255, 255, 255, 0.65);
    --border: rgba(255, 255, 255, 0.14);
    --accent: #4ea6f2;
    --accent-hover: #6bb6f5;
  }
}

* {
  box-sizing: border-box;
}

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

body {
  margin: 0;
  padding: 0 20px;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Helvetica Neue", "Hiragino Sans",
    "Hiragino Kaku Gothic ProN", "Noto Sans JP", Meiryo, sans-serif;
  line-height: 1.8;
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
}

.container {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 48px 0 80px;
}

header.site-header {
  border-bottom: 1px solid var(--border);
  padding-bottom: 24px;
  margin-bottom: 32px;
}

header.site-header .app-name {
  font-size: 14px;
  color: var(--text-muted);
  margin: 0 0 4px;
  letter-spacing: 0.02em;
}

h1 {
  font-size: 28px;
  line-height: 1.4;
  margin: 0 0 8px;
  font-weight: 700;
}

h2 {
  font-size: 20px;
  margin: 40px 0 12px;
  font-weight: 700;
}

h3 {
  font-size: 16px;
  margin: 24px 0 8px;
  font-weight: 700;
}

p {
  margin: 0 0 16px;
}

ul {
  margin: 0 0 16px;
  padding-left: 1.4em;
}

li {
  margin-bottom: 8px;
}

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

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

.updated {
  font-size: 14px;
  color: var(--text-muted);
  margin: 0;
}

.note {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 16px 20px;
  margin: 20px 0;
}

.note p:last-child {
  margin-bottom: 0;
}

.cards {
  display: grid;
  gap: 16px;
  margin-top: 32px;
}

.card {
  display: block;
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px 24px;
  background: var(--surface);
  color: var(--text);
  transition: border-color 0.15s ease;
}

.card:hover {
  border-color: var(--accent);
  text-decoration: none;
}

.card .card-title {
  font-size: 18px;
  font-weight: 700;
  margin: 0 0 4px;
}

.card .card-desc {
  font-size: 14px;
  color: var(--text-muted);
  margin: 0;
}

footer.site-footer {
  border-top: 1px solid var(--border);
  margin-top: 56px;
  padding-top: 24px;
  font-size: 14px;
  color: var(--text-muted);
}

footer.site-footer a {
  color: var(--text-muted);
  text-decoration: underline;
}

.back-link {
  display: inline-block;
  margin-bottom: 24px;
  font-size: 14px;
}