#D50017

CSS

:root {
  --heroic-red: #d50017;
  --heroic-red-rgb: 213 0 23;
  --heroic-red-oklch: oklch(0.549 0.224 27);
}

.element {
  color: var(--heroic-red);
  background-color: hsl(354 100% 42%);
  border-color: oklch(0.549 0.224 27);
}

Tailwind CSS v4

@theme {
  --color-heroic-red: #d50017;
  --color-heroic-red-50: #ffded1;
  --color-heroic-red-100: #ffccbd;
  --color-heroic-red-200: #ffae9c;
  --color-heroic-red-300: #ff8472;
  --color-heroic-red-400: #ff5950;
  --color-heroic-red-500: #f81522;
  --color-heroic-red-600: #d11a20;
  --color-heroic-red-700: #a81619;
  --color-heroic-red-800: #7e0c15;
  --color-heroic-red-900: #59080d;
  --color-heroic-red-950: #3c0002;
}

SCSS

$heroic-red: #d50017;
$heroic-red-rgb: 213, 0, 23;
$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);
}