#D6171B

CSS

:root {
  --heroic-red: #d6171b;
  --heroic-red-rgb: 214 23 27;
  --heroic-red-oklch: oklch(0.558 0.218 27.7);
}

.element {
  color: var(--heroic-red);
  background-color: hsl(359 81% 46%);
  border-color: oklch(0.558 0.218 27.7);
}

Tailwind CSS v4

@theme {
  --color-heroic-red: #d6171b;
  --color-heroic-red-50: #ffded1;
  --color-heroic-red-100: #ffcdbd;
  --color-heroic-red-200: #ffaf9d;
  --color-heroic-red-300: #ff8673;
  --color-heroic-red-400: #ff5c50;
  --color-heroic-red-500: #f52023;
  --color-heroic-red-600: #cf2120;
  --color-heroic-red-700: #a71b1a;
  --color-heroic-red-800: #7d1015;
  --color-heroic-red-900: #580b0d;
  --color-heroic-red-950: #3b0002;
}

SCSS

$heroic-red: #d6171b;
$heroic-red-rgb: 214, 23, 27;
$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);
}