#040807

CSS

:root {
  --black-metal: #040807;
  --black-metal-rgb: 4 8 7;
  --black-metal-oklch: oklch(0.128 0.009 179.9);
}

.element {
  color: var(--black-metal);
  background-color: hsl(165 33% 2%);
  border-color: oklch(0.128 0.009 179.9);
}

Tailwind CSS v4

@theme {
  --color-black-metal: #040807;
  --color-black-metal-50: #f2f6f5;
  --color-black-metal-100: #e5e9e8;
  --color-black-metal-200: #d0d5d4;
  --color-black-metal-300: #b2b9b8;
  --color-black-metal-400: #99a09e;
  --color-black-metal-500: #808886;
  --color-black-metal-600: #6c7372;
  --color-black-metal-700: #575c5b;
  --color-black-metal-800: #3f4342;
  --color-black-metal-900: #2b2f2e;
  --color-black-metal-950: #191b1b;
}

SCSS

$black-metal: #040807;
$black-metal-rgb: 4, 8, 7;
$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);
}