:root {
  --bg: #FAFAF8;
  --text: #1F2933;
  --muted: #5B6770;
  --accent: #3E5C76;
  --border: #E1E4E8;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16191D;
    --text: #E8EAED;
    --muted: #9AA5AD;
    --accent: #8FB0CC;
    --border: #2E3439;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Yu Gothic UI", sans-serif;
  line-height: 1.9;
}
main { max-width: 680px; margin: 0 auto; padding: 48px 20px 80px; }
h1 { font-size: 1.5rem; font-weight: 600; }
h2 { font-size: 1.1rem; font-weight: 600; margin-top: 2.5em; padding-bottom: 6px; border-bottom: 1px solid var(--border); }
h3 { font-size: 0.95rem; font-weight: 600; margin: 1.6em 0 0; }
h3 + p { margin-top: 0; }
p, li { font-size: 0.95rem; }
ul { padding-left: 1.4em; }
.meta { color: var(--muted); font-size: 0.85rem; }
.lang { margin: 0; text-align: right; font-size: 0.85rem; }
a { color: var(--accent); }
footer { max-width: 680px; margin: 0 auto; padding: 0 20px 48px; color: var(--muted); font-size: 0.85rem; }