:root {
  color-scheme: light;
  --background: #f8fafc;
  --surface: #ffffff;
  --text: #0f172a;
  --muted: #475569;
  --border: #e2e8f0;
  --link: #2563eb;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--background);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", sans-serif;
  line-height: 1.75;
}

main {
  max-width: 860px;
  margin: 0 auto;
  padding: 48px 20px 72px;
}

header {
  margin-bottom: 32px;
}

h1 {
  margin: 0 0 12px;
  font-size: 32px;
  line-height: 1.25;
}

h2 {
  margin: 36px 0 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
  font-size: 22px;
  line-height: 1.35;
}

h3 {
  margin: 24px 0 8px;
  font-size: 18px;
  line-height: 1.4;
}

p,
li {
  font-size: 16px;
}

ul {
  padding-left: 24px;
}

a {
  color: var(--link);
}

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

.card {
  margin: 20px 0;
  padding: 20px;
  border: 1px solid var(--border);
  border-radius: 12px;
  background: var(--surface);
}

.nav-list {
  display: grid;
  gap: 12px;
  padding: 0;
  list-style: none;
}

.nav-list a {
  display: block;
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: 10px;
  background: var(--surface);
  text-decoration: none;
  font-weight: 600;
}

footer {
  margin-top: 40px;
  color: var(--muted);
  font-size: 14px;
}