#D70F32

CSS

:root {
  --rare-red: #d70f32;
  --rare-red-rgb: 215 15 50;
  --rare-red-oklch: oklch(0.559 0.22 22.2);
}

.element {
  color: var(--rare-red);
  background-color: hsl(350 87% 45%);
  border-color: oklch(0.559 0.22 22.2);
}

Tailwind CSS v4

@theme {
  --color-rare-red: #d70f32;
  --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: #f6173c;
  --color-rare-red-600: #d01b34;
  --color-rare-red-700: #a71729;
  --color-rare-red-800: #7d0d20;
  --color-rare-red-900: #590915;
  --color-rare-red-950: #3b0007;
}

SCSS

$rare-red: #d70f32;
$rare-red-rgb: 215, 15, 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);
}