:root {
  --bg: #fafafa;
  --text: #1c1b1f;
  --muted: #5f5b66;
  --accent: #2e7d32;
  --card: #ffffff;
  --line: #e2e0e6;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #101114;
    --text: #e6e1e9;
    --muted: #a9a4b0;
    --accent: #81c784;
    --card: #1b1c20;
    --line: #2f3035;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  line-height: 1.6;
}

header, main, footer {
  max-width: 44rem;
  margin: 0 auto;
  padding: 1rem 1rem;
}

header { padding-top: 1.5rem; border-bottom: 1px solid var(--line); }
header a.brand { color: var(--text); font-weight: 700; font-size: 1.2rem; text-decoration: none; }
nav { margin-top: 0.4rem; }
nav a { margin-right: 1rem; color: var(--accent); }

h1 { font-size: 1.9rem; line-height: 1.25; margin: 1.2rem 0 0.6rem; }
h2 { font-size: 1.25rem; margin: 2rem 0 0.4rem; }
p, li { color: var(--text); }
.muted { color: var(--muted); font-size: 0.95rem; }
a { color: var(--accent); }

.card {
  background: var(--card);
  border: 1px solid var(--line);
  border-radius: 0.75rem;
  padding: 1rem 1.2rem;
  margin: 1rem 0;
}

.todo { background: #fff3cd; color: #5c4400; padding: 0 0.25rem; border-radius: 0.2rem; }

footer { border-top: 1px solid var(--line); margin-top: 2rem; color: var(--muted); font-size: 0.9rem; }