#DA0018

CSS

:root {
  --heroic-red: #da0018;
  --heroic-red-rgb: 218 0 24;
  --heroic-red-oklch: oklch(0.559 0.228 26.9);
}

.element {
  color: var(--heroic-red);
  background-color: hsl(353 100% 43%);
  border-color: oklch(0.559 0.228 26.9);
}

Tailwind CSS v4

@theme {
  --color-heroic-red: #da0018;
  --color-heroic-red-50: #ffddd0;
  --color-heroic-red-100: #ffcbbc;
  --color-heroic-red-200: #ffad9b;
  --color-heroic-red-300: #ff8371;
  --color-heroic-red-400: #ff574e;
  --color-heroic-red-500: #f9081f;
  --color-heroic-red-600: #d3141d;
  --color-heroic-red-700: #aa1217;
  --color-heroic-red-800: #7f0814;
  --color-heroic-red-900: #5a070c;
  --color-heroic-red-950: #3c0002;
}

SCSS

$heroic-red: #da0018;
$heroic-red-rgb: 218, 0, 24;
$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);
}