#D51B1D

CSS

:root {
  --heroic-red: #d51b1d;
  --heroic-red-rgb: 213 27 29;
  --heroic-red-oklch: oklch(0.558 0.215 27.7);
}

.element {
  color: var(--heroic-red);
  background-color: hsl(359 78% 47%);
  border-color: oklch(0.558 0.215 27.7);
}

Tailwind CSS v4

@theme {
  --color-heroic-red: #d51b1d;
  --color-heroic-red-50: #ffdfd1;
  --color-heroic-red-100: #ffcdbe;
  --color-heroic-red-200: #ffb09d;
  --color-heroic-red-300: #ff8774;
  --color-heroic-red-400: #ff5d51;
  --color-heroic-red-500: #f42425;
  --color-heroic-red-600: #ce2422;
  --color-heroic-red-700: #a61d1b;
  --color-heroic-red-800: #7c1216;
  --color-heroic-red-900: #580c0e;
  --color-heroic-red-950: #3b0002;
}

SCSS

$heroic-red: #d51b1d;
$heroic-red-rgb: 213, 27, 29;
$heroic-red-light: mix(#fff, $heroic-red, 20%);
$heroic-red-dark: mix(#000, $heroic-red, 20%);

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