#5B3200

CSS

:root {
  --brown: #5b3200;
  --brown-rgb: 91 50 0;
  --brown-oklch: oklch(0.361 0.082 63.1);
}

.element {
  color: var(--brown);
  background-color: hsl(33 100% 18%);
  border-color: oklch(0.361 0.082 63.1);
}

Tailwind CSS v4

@theme {
  --color-brown: #5b3200;
  --color-brown-50: #fff1dd;
  --color-brown-100: #fce3cc;
  --color-brown-200: #eeceb0;
  --color-brown-300: #d5af8b;
  --color-brown-400: #c2946b;
  --color-brown-500: #ad7a4a;
  --color-brown-600: #92673f;
  --color-brown-700: #755232;
  --color-brown-800: #573c24;
  --color-brown-900: #3d2918;
  --color-brown-950: #261709;
}

SCSS

$brown: #5b3200;
$brown-rgb: 91, 50, 0;
$brown-light: mix(#fff, $brown, 20%);
$brown-dark: mix(#000, $brown, 20%);

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