:root {
  --bg: #fbfbfa;
  --surface: #ffffff;
  --text: #1c1c1a;
  --muted: #61615c;
  --line: #e4e3df;
  --accent: #2f6f5e;
  --accent-soft: #eef4f2;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #131315;
    --surface: #1b1b1e;
    --text: #ececea;
    --muted: #9a9a94;
    --line: #2e2e32;
    --accent: #7fc4ad;
    --accent-soft: #1e2a27;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", Arial,
    "Hiragino Sans", "Noto Sans JP", sans-serif;
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

.wrap {
  max-width: 720px;
  margin: 0 auto;
  padding: 0 20px;
}

header {
  border-bottom: 1px solid var(--line);
  padding-block: 20px;
  margin-bottom: 56px;
}

header .wrap {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  align-items: baseline;
  justify-content: space-between;
}

.brand {
  font-size: 17px;
  font-weight: 650;
  letter-spacing: -0.01em;
  text-decoration: none;
  color: var(--text);
}

nav a {
  color: var(--muted);
  text-decoration: none;
  font-size: 15px;
  margin-left: 20px;
}

nav a:first-child { margin-left: 0; }
nav a:hover { color: var(--accent); }

h1 {
  font-size: 30px;
  line-height: 1.3;
  letter-spacing: -0.02em;
  margin: 0 0 16px;
}

h2 {
  font-size: 19px;
  letter-spacing: -0.01em;
  margin: 48px 0 14px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
}

h3 { font-size: 16px; margin: 28px 0 8px; }

p { margin: 0 0 16px; }

.lede {
  font-size: 18px;
  color: var(--muted);
  margin-bottom: 40px;
}

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

.card {
  background: var(--surface);
  border: 1px solid var(--line);
  border-radius: 10px;
  padding: 22px 24px;
  margin-bottom: 16px;
}

.card h3 { margin-top: 0; }

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

.tag {
  display: inline-block;
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--accent);
  background: var(--accent-soft);
  border-radius: 999px;
  padding: 3px 10px;
  margin-left: 8px;
  vertical-align: 2px;
}

dl { margin: 0; }
dt { font-weight: 650; margin-top: 22px; }
dd { margin: 6px 0 0; color: var(--muted); }

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.9em;
  background: var(--accent-soft);
  border-radius: 4px;
  padding: 1px 5px;
}

footer {
  margin-top: 72px;
  border-top: 1px solid var(--line);
  padding-block: 24px 48px;
  color: var(--muted);
  font-size: 14px;
}

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