#DA002C

CSS

:root {
  --rare-red: #da002c;
  --rare-red-rgb: 218 0 44;
  --rare-red-oklch: oklch(0.56 0.226 23.2);
}

.element {
  color: var(--rare-red);
  background-color: hsl(348 100% 43%);
  border-color: oklch(0.56 0.226 23.2);
}

Tailwind CSS v4

@theme {
  --color-rare-red: #da002c;
  --color-rare-red-50: #ffddd4;
  --color-rare-red-100: #ffcac1;
  --color-rare-red-200: #ffaca2;
  --color-rare-red-300: #ff827a;
  --color-rare-red-400: #ff565b;
  --color-rare-red-500: #f90534;
  --color-rare-red-600: #d2122e;
  --color-rare-red-700: #a91124;
  --color-rare-red-800: #7e081c;
  --color-rare-red-900: #5a0612;
  --color-rare-red-950: #3c0005;
}

SCSS

$rare-red: #da002c;
$rare-red-rgb: 218, 0, 44;
$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);
}