/* Design tokens for The History of AI (reskin: "Midnight & Signal").
   Palette: warm paper, midnight violet ink, electric violet for action,
   signal magenta for highlights, gold for focus and sparks.
   Every text/background pair below meets WCAG AA (4.5:1) or better. */
:root {
  /* Colour: surfaces */
  --color-paper: #fbf9f4;        /* page background */
  --color-mist: #efeafc;         /* cards, alternate bands (lavender tint) */
  --color-deep: #150d2e;         /* dark bands, hero, footer */
  /* Colour: text */
  --color-ink: #1c1533;          /* body text on paper 16.6:1, on mist 14.8:1 */
  --color-ink-soft: #52496b;     /* secondary text on paper 7.9:1, on mist 7.1:1 */
  --color-on-deep: #fbf9f4;      /* text on deep 17.7:1 */
  /* Colour: accents */
  --color-primary: #5a2bd6;      /* links, buttons on paper 7.3:1; white on it 7.6:1 */
  --color-highlight: #b8236b;    /* dates, eyebrows on paper 5.7:1, on mist 5.1:1 */
  --color-primary-light: #b9a4ff; /* links on deep 8.7:1 */
  --color-highlight-light: #ff9ec7; /* highlights on deep 9.7:1 */
  --color-gold: #ffc857;         /* sparks, focus ring on deep 12.1:1 */
  --color-focus: #ffc857;
  --color-line: #d9d2ec;         /* borders and rules */

  /* Gradients for hero and bands */
  --gradient-deep: linear-gradient(135deg, #150d2e 0%, #2a1466 60%, #4a1d8f 100%);
  --gradient-spark: linear-gradient(90deg, #5a2bd6, #b8236b);

  /* Type: system fonts only */
  --font-body: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --font-display: "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --font-mono: ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  --weight-display: 700;

  /* Type scale (1.333 ratio, fluid at the top end) */
  --text-xs: 0.8rem;
  --text-sm: 0.925rem;
  --text-base: 1.125rem;
  --text-lg: 1.375rem;
  --text-xl: clamp(1.6rem, 1.3rem + 1vw, 1.95rem);
  --text-2xl: clamp(2.1rem, 1.6rem + 2vw, 3rem);
  --text-3xl: clamp(2.8rem, 1.8rem + 4.5vw, 5rem);
  --leading-tight: 1.1;
  --leading-body: 1.65;
  --measure: 65ch;               /* comfortable line length */

  /* Spacing */
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.75rem;
  --space-6: 3rem;
  --space-7: 5rem;

  /* Shape */
  --radius-sm: 6px;
  --radius-md: 14px;
  --radius-lg: 24px;
  --shadow-card: 0 1px 2px rgba(21, 13, 46, 0.08), 0 8px 24px rgba(21, 13, 46, 0.1);
  --content-width: 70rem;

  /* Aliases kept so existing stylesheets keep working */
  --color-navy: var(--color-deep);
  --color-on-navy: var(--color-on-deep);
  --color-teal: var(--color-primary);
  --color-amber: var(--color-highlight);
  --color-teal-light: var(--color-primary-light);
  --color-amber-light: var(--color-highlight-light);
  --color-bg: var(--color-paper);
  --color-text: var(--color-ink);
  --color-accent: var(--color-primary);
  --space: var(--space-4);
}