#647238

CSS

:root {
  --muddy-green: #647238;
  --muddy-green-rgb: 100 114 56;
  --muddy-green-oklch: oklch(0.526 0.084 120.5);
}

.element {
  color: var(--muddy-green);
  background-color: hsl(74 34% 33%);
  border-color: oklch(0.526 0.084 120.5);
}

Tailwind CSS v4

@theme {
  --color-muddy-green: #647238;
  --color-muddy-green-50: #f1fadf;
  --color-muddy-green-100: #e3edce;
  --color-muddy-green-200: #cedbb3;
  --color-muddy-green-300: #afbf8f;
  --color-muddy-green-400: #97a66e;
  --color-muddy-green-500: #7e8f4d;
  --color-muddy-green-600: #6b7942;
  --color-muddy-green-700: #556134;
  --color-muddy-green-800: #3f4624;
  --color-muddy-green-900: #2c3118;
  --color-muddy-green-950: #191d09;
}

SCSS

$muddy-green: #647238;
$muddy-green-rgb: 100, 114, 56;
$muddy-green-light: mix(#fff, $muddy-green, 20%);
$muddy-green-dark: mix(#000, $muddy-green, 20%);

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