:root {
  --bg: #fbfaf7;
  --fg: #2b2a28;
  --muted: #6b6862;
  --accent: #3d7fc4;
  --card: #ffffff;
  --line: #e6e2da;
  color-scheme: light dark;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #1c1c1e;
    --fg: #ecebe8;
    --muted: #a3a09a;
    --accent: #7db3ea;
    --card: #2a2a2c;
    --line: #3a3a3c;
  }
}
* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Hiragino Sans", "Hiragino Kaku Gothic ProN", "Noto Sans JP", sans-serif;
  line-height: 1.8;
  font-size: 16px;
}
main { max-width: 720px; margin: 0 auto; padding: 32px 16px 64px; }
h1 { font-size: 1.6rem; line-height: 1.4; margin: 0 0 8px; }
h2 { font-size: 1.15rem; margin: 2em 0 0.5em; padding-bottom: 4px; border-bottom: 1px solid var(--line); }
h3 { font-size: 1rem; margin: 1.5em 0 0.25em; }
p, li { overflow-wrap: anywhere; }
.meta { color: var(--muted); font-size: 0.9rem; }
.card { background: var(--card); border: 1px solid var(--line); border-radius: 12px; padding: 16px; margin: 16px 0; }
a { color: var(--accent); }
nav { display: flex; gap: 16px; flex-wrap: wrap; margin-bottom: 24px; font-size: 0.95rem; }
footer { margin-top: 48px; color: var(--muted); font-size: 0.85rem; }
.todo { background: #fff3c4; color: #5c4400; padding: 0 4px; border-radius: 4px; }