#E53A00

CSS

:root {
  --vulcan-fire: #e53a00;
  --vulcan-fire-rgb: 229 58 0;
  --vulcan-fire-oklch: oklch(0.606 0.214 34.8);
}

.element {
  color: var(--vulcan-fire);
  background-color: hsl(15 100% 45%);
  border-color: oklch(0.606 0.214 34.8);
}

Tailwind CSS v4

@theme {
  --color-vulcan-fire: #e53a00;
  --color-vulcan-fire-50: #ffe0ca;
  --color-vulcan-fire-100: #ffcfb6;
  --color-vulcan-fire-200: #ffb292;
  --color-vulcan-fire-300: #ff8b64;
  --color-vulcan-fire-400: #ff623b;
  --color-vulcan-fire-500: #f22e00;
  --color-vulcan-fire-600: #cd2b00;
  --color-vulcan-fire-700: #a52300;
  --color-vulcan-fire-800: #7b1602;
  --color-vulcan-fire-900: #570f02;
  --color-vulcan-fire-950: #3a0000;
}

SCSS

$vulcan-fire: #e53a00;
$vulcan-fire-rgb: 229, 58, 0;
$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);
}