#663D25

CSS

:root {
  --van-dyke-brown: #663d25;
  --van-dyke-brown-rgb: 102 61 37;
  --van-dyke-brown-oklch: oklch(0.404 0.068 50.2);
}

.element {
  color: var(--van-dyke-brown);
  background-color: hsl(22 47% 27%);
  border-color: oklch(0.404 0.068 50.2);
}

Tailwind CSS v4

@theme {
  --color-van-dyke-brown: #663d25;
  --color-van-dyke-brown-50: #fff0e4;
  --color-van-dyke-brown-100: #fbe2d3;
  --color-van-dyke-brown-200: #edcdba;
  --color-van-dyke-brown-300: #d5ae98;
  --color-van-dyke-brown-400: #c0937a;
  --color-van-dyke-brown-500: #ab795d;
  --color-van-dyke-brown-600: #91674f;
  --color-van-dyke-brown-700: #74523f;
  --color-van-dyke-brown-800: #563b2d;
  --color-van-dyke-brown-900: #3c291f;
  --color-van-dyke-brown-950: #26160e;
}

SCSS

$van-dyke-brown: #663d25;
$van-dyke-brown-rgb: 102, 61, 37;
$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);
}