#040404

CSS

:root {
  --black-metal: #040404;
  --black-metal-rgb: 4 4 4;
  --black-metal-oklch: oklch(0.107 0 0);
}

.element {
  color: var(--black-metal);
  background-color: hsl(0 0% 2%);
  border-color: oklch(0.107 0 0);
}

Tailwind CSS v4

@theme {
  --color-black-metal: #040404;
  --color-black-metal-50: #f5f5f5;
  --color-black-metal-100: #e8e8e8;
  --color-black-metal-200: #d4d4d4;
  --color-black-metal-300: #b7b7b7;
  --color-black-metal-400: #9e9e9e;
  --color-black-metal-500: #868686;
  --color-black-metal-600: #717171;
  --color-black-metal-700: #5b5b5b;
  --color-black-metal-800: #424242;
  --color-black-metal-900: #2e2e2e;
  --color-black-metal-950: #1b1b1b;
}

SCSS

$black-metal: #040404;
$black-metal-rgb: 4, 4, 4;
$black-metal-light: mix(#fff, $black-metal, 20%);
$black-metal-dark: mix(#000, $black-metal, 20%);

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