#040706

CSS

:root {
  --black-metal: #040706;
  --black-metal-rgb: 4 7 6;
  --black-metal-oklch: oklch(0.123 0.008 174.7);
}

.element {
  color: var(--black-metal);
  background-color: hsl(160 27% 2%);
  border-color: oklch(0.123 0.008 174.7);
}

Tailwind CSS v4

@theme {
  --color-black-metal: #040706;
  --color-black-metal-50: #f3f6f5;
  --color-black-metal-100: #e5e9e8;
  --color-black-metal-200: #d1d5d4;
  --color-black-metal-300: #b3b9b7;
  --color-black-metal-400: #9aa09e;
  --color-black-metal-500: #818886;
  --color-black-metal-600: #6d7371;
  --color-black-metal-700: #575c5a;
  --color-black-metal-800: #404342;
  --color-black-metal-900: #2c2e2e;
  --color-black-metal-950: #191b1a;
}

SCSS

$black-metal: #040706;
$black-metal-rgb: 4, 7, 6;
$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);
}