:root {
  color-scheme: light;
  /* AQI3 brand primitives */
  --brand-charcoal-950: #1a1c20;
  --brand-charcoal-900: #202124;
  --brand-charcoal-800: #2f3439;
  --brand-charcoal-700: #404851;
  --brand-lime-500: #abe91e;
  --brand-lime-700: #537a00;
  --brand-lime-100: #efffc9;

  /* Semantic colours */
  --color-page: #f6f7f2;
  --color-surface: #ffffff;
  --color-surface-subtle: #f1f3ed;
  --color-text: var(--brand-charcoal-900);
  --color-text-muted: #5d666c;
  --color-border: #dce1d7;
  --color-border-strong: #b8c2b3;
  --color-primary: var(--brand-charcoal-900);
  --color-accent: var(--brand-lime-500);
  --color-accent-ink: #324b00;
  --color-accent-soft: #efffc9;
  --color-on-accent: #202124;
  --color-warning: #975a08;
  --color-warning-soft: #fff3dc;
  --color-selected: #202124;
  --color-selected-text: #ffffff;
  --color-on-dark: #f4f7f8;
  --color-on-dark-muted: #d2d9dc;
  --color-on-dark-subtle: #adb7bc;
  --color-logo-tile: #eef2eb;
  --color-logo-caption: #3f494f;
  --color-ring: #3d6500;

  /* Typography */
  --font-body: "Segoe UI Variable", "Segoe UI", system-ui, sans-serif;
  --font-mono: "Cascadia Code", "SFMono-Regular", Consolas, monospace;
  --text-xs: .75rem;
  --text-sm: .875rem;
  --text-base: 1rem;
  --text-lg: 1.125rem;
  --text-xl: 1.25rem;
  --text-2xl: 1.5rem;
  --text-3xl: 2rem;
  --text-display: clamp(2.55rem, 6.4vw, 4.75rem);

  /* Spacing and shape */
  --space-1: .25rem;
  --space-2: .5rem;
  --space-3: .75rem;
  --space-4: 1rem;
  --space-5: 1.5rem;
  --space-6: 2rem;
  --space-7: 3rem;
  --space-8: 4.5rem;
  --radius-sm: .5rem;
  --radius-md: .8rem;
  --radius-lg: 1.1rem;
  --radius-xl: 1.5rem;
  --shadow-card: 0 10px 30px rgba(32, 33, 36, .07);
  --content-width: 70rem;
  --reading-width: 72ch;
}

[data-theme="dark"] {
  color-scheme: dark;
  --color-page: #101214;
  --color-surface: #1b1f22;
  --color-surface-subtle: #252a2e;
  --color-text: #eef2f3;
  --color-text-muted: #b7c0c5;
  --color-border: #41484e;
  --color-border-strong: #667078;
  --color-primary: var(--brand-lime-500);
  --color-accent-ink: #b9ef3c;
  --color-accent-soft: #263315;
  --color-warning: #ffb34d;
  --color-warning-soft: #332719;
  --color-selected: #3b444a;
  --color-selected-text: #ffffff;
  --color-ring: #b9ef3c;
  --shadow-card: 0 12px 34px rgba(0, 0, 0, .24);
}