#DE370D

CSS

:root {
  --vulcan-fire: #de370d;
  --vulcan-fire-rgb: 222 55 13;
  --vulcan-fire-oklch: oklch(0.592 0.208 33.7);
}

.element {
  color: var(--vulcan-fire);
  background-color: hsl(12 89% 46%);
  border-color: oklch(0.592 0.208 33.7);
}

Tailwind CSS v4

@theme {
  --color-vulcan-fire: #de370d;
  --color-vulcan-fire-50: #ffe1cc;
  --color-vulcan-fire-100: #ffcfb8;
  --color-vulcan-fire-200: #ffb396;
  --color-vulcan-fire-300: #ff8c69;
  --color-vulcan-fire-400: #ff6442;
  --color-vulcan-fire-500: #f03200;
  --color-vulcan-fire-600: #cb2e03;
  --color-vulcan-fire-700: #a32505;
  --color-vulcan-fire-800: #7a1808;
  --color-vulcan-fire-900: #571006;
  --color-vulcan-fire-950: #3a0100;
}

SCSS

$vulcan-fire: #de370d;
$vulcan-fire-rgb: 222, 55, 13;
$vulcan-fire-light: mix(#fff, $vulcan-fire, 20%);
$vulcan-fire-dark: mix(#000, $vulcan-fire, 20%);

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