#003421

CSS

:root {
  --pitch-black-forests: #003421;
  --pitch-black-forests-rgb: 0 52 33;
  --pitch-black-forests-oklch: oklch(0.287 0.063 162.3);
}

.element {
  color: var(--pitch-black-forests);
  background-color: hsl(158 100% 10%);
  border-color: oklch(0.287 0.063 162.3);
}

Tailwind CSS v4

@theme {
  --color-pitch-black-forests: #003421;
  --color-pitch-black-forests-50: #e6fbf0;
  --color-pitch-black-forests-100: #d6efe2;
  --color-pitch-black-forests-200: #bdddcd;
  --color-pitch-black-forests-300: #9ac2af;
  --color-pitch-black-forests-400: #7daa93;
  --color-pitch-black-forests-500: #5f937a;
  --color-pitch-black-forests-600: #517d67;
  --color-pitch-black-forests-700: #406452;
  --color-pitch-black-forests-800: #2f493b;
  --color-pitch-black-forests-900: #203328;
  --color-pitch-black-forests-950: #0f1e16;
}

SCSS

$pitch-black-forests: #003421;
$pitch-black-forests-rgb: 0, 52, 33;
$pitch-black-forests-light: mix(#fff, $pitch-black-forests, 20%);
$pitch-black-forests-dark: mix(#000, $pitch-black-forests, 20%);

.element {
  color: $pitch-black-forests;
  box-shadow: 0 0 0 2px rgba($pitch-black-forests, 0.35);
}