#643E1F

CSS

:root {
  --van-dyke-brown: #643e1f;
  --van-dyke-brown-rgb: 100 62 31;
  --van-dyke-brown-oklch: oklch(0.402 0.07 58.1);
}

.element {
  color: var(--van-dyke-brown);
  background-color: hsl(27 53% 26%);
  border-color: oklch(0.402 0.07 58.1);
}

Tailwind CSS v4

@theme {
  --color-van-dyke-brown: #643e1f;
  --color-van-dyke-brown-50: #fff1e2;
  --color-van-dyke-brown-100: #fae3d1;
  --color-van-dyke-brown-200: #ebceb7;
  --color-van-dyke-brown-300: #d3b094;
  --color-van-dyke-brown-400: #be9576;
  --color-van-dyke-brown-500: #a97b57;
  --color-van-dyke-brown-600: #8f684a;
  --color-van-dyke-brown-700: #73533b;
  --color-van-dyke-brown-800: #553c2a;
  --color-van-dyke-brown-900: #3b291c;
  --color-van-dyke-brown-950: #25170d;
}

SCSS

$van-dyke-brown: #643e1f;
$van-dyke-brown-rgb: 100, 62, 31;
$van-dyke-brown-light: mix(#fff, $van-dyke-brown, 20%);
$van-dyke-brown-dark: mix(#000, $van-dyke-brown, 20%);

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