#816A18

CSS

:root {
  --muddy-brown: #816a18;
  --muddy-brown-rgb: 129 106 24;
  --muddy-brown-oklch: oklch(0.532 0.1 92.2);
}

.element {
  color: var(--muddy-brown);
  background-color: hsl(47 69% 30%);
  border-color: oklch(0.532 0.1 92.2);
}

Tailwind CSS v4

@theme {
  --color-muddy-brown: #816a18;
  --color-muddy-brown-50: #fef5d6;
  --color-muddy-brown-100: #f2e8c3;
  --color-muddy-brown-200: #e2d4a4;
  --color-muddy-brown-300: #c8b77c;
  --color-muddy-brown-400: #b39d56;
  --color-muddy-brown-500: #9e842b;
  --color-muddy-brown-600: #856f26;
  --color-muddy-brown-700: #6b591e;
  --color-muddy-brown-800: #504114;
  --color-muddy-brown-900: #372d0c;
  --color-muddy-brown-950: #221901;
}

SCSS

$muddy-brown: #816a18;
$muddy-brown-rgb: 129, 106, 24;
$muddy-brown-light: mix(#fff, $muddy-brown, 20%);
$muddy-brown-dark: mix(#000, $muddy-brown, 20%);

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