#BC4513

CSS

:root {
  --copper-hopper: #bc4513;
  --copper-hopper-rgb: 188 69 19;
  --copper-hopper-oklch: oklch(0.549 0.164 39.6);
}

.element {
  color: var(--copper-hopper);
  background-color: hsl(18 82% 41%);
  border-color: oklch(0.549 0.164 39.6);
}

Tailwind CSS v4

@theme {
  --color-copper-hopper: #bc4513;
  --color-copper-hopper-50: #ffe7d1;
  --color-copper-hopper-100: #ffd7be;
  --color-copper-hopper-200: #ffbd9d;
  --color-copper-hopper-300: #fd9a73;
  --color-copper-hopper-400: #ed784f;
  --color-copper-hopper-500: #db551f;
  --color-copper-hopper-600: #b9491d;
  --color-copper-hopper-700: #953a17;
  --color-copper-hopper-800: #6f2912;
  --color-copper-hopper-900: #4f1b0b;
  --color-copper-hopper-950: #340b01;
}

SCSS

$copper-hopper: #bc4513;
$copper-hopper-rgb: 188, 69, 19;
$copper-hopper-light: mix(#fff, $copper-hopper, 20%);
$copper-hopper-dark: mix(#000, $copper-hopper, 20%);

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