#D71132

CSS

:root {
  --rare-red: #d71132;
  --rare-red-rgb: 215 17 50;
  --rare-red-oklch: oklch(0.56 0.219 22.3);
}

.element {
  color: var(--rare-red);
  background-color: hsl(350 85% 45%);
  border-color: oklch(0.56 0.219 22.3);
}

Tailwind CSS v4

@theme {
  --color-rare-red: #d71132;
  --color-rare-red-50: #ffddd6;
  --color-rare-red-100: #ffcbc4;
  --color-rare-red-200: #ffada6;
  --color-rare-red-300: #ff847e;
  --color-rare-red-400: #ff5960;
  --color-rare-red-500: #f6193b;
  --color-rare-red-600: #cf1c33;
  --color-rare-red-700: #a71829;
  --color-rare-red-800: #7d0d20;
  --color-rare-red-900: #580915;
  --color-rare-red-950: #3b0007;
}

SCSS

$rare-red: #d71132;
$rare-red-rgb: 215, 17, 50;
$rare-red-light: mix(#fff, $rare-red, 20%);
$rare-red-dark: mix(#000, $rare-red, 20%);

.element {
  color: $rare-red;
  box-shadow: 0 0 0 2px rgba($rare-red, 0.35);
}