#003726

CSS

:root {
  --pitch-black-forests: #003726;
  --pitch-black-forests-rgb: 0 55 38;
  --pitch-black-forests-oklch: oklch(0.299 0.062 165.8);
}

.element {
  color: var(--pitch-black-forests);
  background-color: hsl(161 100% 11%);
  border-color: oklch(0.299 0.062 165.8);
}

Tailwind CSS v4

@theme {
  --color-pitch-black-forests: #003726;
  --color-pitch-black-forests-50: #e5fbf2;
  --color-pitch-black-forests-100: #d5efe4;
  --color-pitch-black-forests-200: #bcddcf;
  --color-pitch-black-forests-300: #99c2b1;
  --color-pitch-black-forests-400: #7bab96;
  --color-pitch-black-forests-500: #5d947d;
  --color-pitch-black-forests-600: #4f7d69;
  --color-pitch-black-forests-700: #3f6454;
  --color-pitch-black-forests-800: #2e493c;
  --color-pitch-black-forests-900: #1f332a;
  --color-pitch-black-forests-950: #0e1e17;
}

SCSS

$pitch-black-forests: #003726;
$pitch-black-forests-rgb: 0, 55, 38;
$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);
}