#030A07

CSS

:root {
  --black-metal: #030a07;
  --black-metal-rgb: 3 10 7;
  --black-metal-oklch: oklch(0.134 0.016 169.2);
}

.element {
  color: var(--black-metal);
  background-color: hsl(154 54% 3%);
  border-color: oklch(0.134 0.016 169.2);
}

Tailwind CSS v4

@theme {
  --color-black-metal: #030a07;
  --color-black-metal-50: #f1f7f4;
  --color-black-metal-100: #e3eae7;
  --color-black-metal-200: #ced7d3;
  --color-black-metal-300: #b0bab6;
  --color-black-metal-400: #96a29d;
  --color-black-metal-500: #7c8a84;
  --color-black-metal-600: #697570;
  --color-black-metal-700: #545d59;
  --color-black-metal-800: #3d4441;
  --color-black-metal-900: #2a2f2d;
  --color-black-metal-950: #181c1a;
}

SCSS

$black-metal: #030a07;
$black-metal-rgb: 3, 10, 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);
}