Birch

CSS

:root {
  --birch: #3f3726;
  --birch-rgb: 63 55 38;
  --birch-oklch: oklch(0.34 0.03 85.6);
}

.element {
  color: var(--birch);
  background-color: hsl(41 25% 20%);
  border-color: oklch(0.34 0.03 85.6);
}

Tailwind CSS v4

@theme {
  --color-birch: #3f3726;
  --color-birch-50: #f9f5ec;
  --color-birch-100: #ece7dd;
  --color-birch-200: #dad4c6;
  --color-birch-300: #beb7a6;
  --color-birch-400: #a69e8b;
  --color-birch-500: #8f8570;
  --color-birch-600: #79715f;
  --color-birch-700: #615a4c;
  --color-birch-800: #474237;
  --color-birch-900: #312d25;
  --color-birch-950: #1d1a14;
}

SCSS

$birch: #3f3726;
$birch-rgb: 63, 55, 38;
$birch-light: mix(#fff, $birch, 20%);
$birch-dark: mix(#000, $birch, 20%);

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