:root {
  --bg: #f4f8fb;
  --card: #ffffff;
  --text: #1f3446;
  --sub: #5b6f80;
  --accent: #1c86c9;
  --line: #dce6ee;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0f2530;
    --card: #17333f;
    --text: #e6f0f5;
    --sub: #a7bcc8;
    --accent: #4fb3f0;
    --line: #28495a;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font: 16px/1.75 -apple-system, BlinkMacSystemFont, "Segoe UI", "Hiragino Sans", "Noto Sans JP", sans-serif;
}
main { max-width: 760px; margin: 0 auto; padding: 32px 16px 64px; }
header { display: flex; align-items: center; gap: 12px; margin-bottom: 8px; }
header img.icon { width: 48px; height: 48px; border-radius: 12px; }
header img.word { height: 36px; }
nav.lang { margin: 8px 0 24px; font-size: 14px; color: var(--sub); }
nav.lang a { margin-right: 12px; }
section { background: var(--card); border: 1px solid var(--line); border-radius: 16px; padding: 20px 24px; margin-bottom: 24px; }
h1 { font-size: 26px; margin: 0 0 4px; }
h2 { font-size: 19px; margin: 28px 0 8px; }
h3 { font-size: 16px; margin: 20px 0 4px; }
p, li { color: var(--text); }
.meta { color: var(--sub); font-size: 14px; }
a { color: var(--accent); }
ul { padding-left: 1.3em; }
footer { color: var(--sub); font-size: 13px; text-align: center; margin-top: 40px; }
@media (prefers-color-scheme: dark) {
  /* The wordmark is dark navy; give it a light plate on dark pages. */
  header img.word { background: #eef5f9; border-radius: 10px; padding: 4px 8px; }
}