:root {
  /* Palette: aged paper, ink, Swiss red, slate blue, brass. An early-1900s academic feel.
     Contrast: --ink on --bg 14:1; --on-accent on --accent 6.9:1; --muted on --bg 7.3:1; --slate on --bg 8.6:1 */
  --bg: #f7f1e3;
  --surface: #ebe2cc;
  --ink: #1c1a17;
  --muted: #4d473d;
  --accent: #b3141b;
  --accent-dark: #86090f;
  --on-accent: #ffffff;
  --slate: #28445f;
  --on-slate: #ffffff;
  --brass: #a67c1f;
  --border: #c9bd9f;
  --focus: #0050d8;

  /* Type: system fonts only. Serif for headings and body, sans for labels. */
  --font-display: Georgia, "Iowan Old Style", "Palatino Linotype", "Times New Roman", serif;
  --font-body: Georgia, "Iowan Old Style", "Palatino Linotype", serif;
  --font-label: system-ui, -apple-system, "Segoe UI", Roboto, Arial, sans-serif;
  --text-sm: 0.875rem;
  --text-base: 1.125rem;
  --text-lg: 1.3rem;
  --text-xl: 1.8rem;
  --text-2xl: clamp(2rem, 5vw, 3rem);
  --text-3xl: clamp(2.5rem, 7vw, 4.25rem);
  --leading: 1.7;
  --leading-tight: 1.15;
  --measure: 66ch;

  /* Spacing and shape: square corners, thin rules, like a printed page */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 1rem;
  --space-4: 1.5rem;
  --space-5: 2.5rem;
  --space-6: 4rem;
  --radius: 0;
  --rule: 1px solid var(--border);
  --max-width: 64rem;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #17150f;
    --surface: #24211a;
    --ink: #f3ecd9;
    --muted: #cfc5ac;
    --accent: #ff6b6f;
    --on-accent: #17150f;
    --slate: #8fb3d6;
    --on-slate: #17150f;
    --brass: #d9b04a;
    --border: #4a4435;
    --focus: #7fb0ff;
  }
}