:root {
  color-scheme: light dark;
  --bg: #ffffff;
  --fg: #1b2430;
  --muted: #5c6b7a;
  --line: #e3e8ee;
  --card: #f7f9fb;
  --accent: #397FB5;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #12171d;
    --fg: #e8edf3;
    --muted: #9aa8b6;
    --line: #27313c;
    --card: #1a212a;
    --accent: #6CB6DF;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Noto Sans JP", "Yu Gothic UI", sans-serif;
  font-size: 16px;
  line-height: 1.9;
  -webkit-text-size-adjust: 100%;
}

.wrap {
  max-width: 680px;
  margin: 0 auto;
  padding: 48px 20px 80px;
}

h1 {
  font-size: 1.75rem;
  line-height: 1.5;
  margin: 0 0 .4em;
  letter-spacing: .02em;
}

h2 {
  font-size: 1.15rem;
  margin: 2.4em 0 .6em;
  padding-top: .6em;
  border-top: 1px solid var(--line);
}

h2:first-of-type { border-top: none; padding-top: 0; }

h3 {
  font-size: 1rem;
  margin: 1.8em 0 .4em;
}

p, li { font-size: 1rem; }

ul { padding-left: 1.3em; }

li { margin-bottom: .4em; }

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

.lead {
  color: var(--muted);
  margin: 0 0 2.5em;
}

.updated {
  color: var(--muted);
  font-size: .9rem;
  margin: 0 0 2em;
}

.card {
  display: block;
  border: 1px solid var(--line);
  background: var(--card);
  border-radius: 14px;
  padding: 18px 20px;
  margin-bottom: 14px;
  text-decoration: none;
  color: inherit;
}

.card:hover { border-color: var(--accent); }

.card strong { display: block; font-size: 1.05rem; margin-bottom: .2em; }

.card span { color: var(--muted); font-size: .9rem; }

.back {
  display: inline-block;
  margin-bottom: 1.5em;
  font-size: .9rem;
  text-decoration: none;
}

footer {
  margin-top: 48px;
  padding-top: 20px;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-size: .85rem;
}