#120506

CSS

:root {
  --dark-matter: #120506;
  --dark-matter-rgb: 18 5 6;
  --dark-matter-oklch: oklch(0.139 0.026 14.6);
}

.element {
  color: var(--dark-matter);
  background-color: hsl(355 57% 5%);
  border-color: oklch(0.139 0.026 14.6);
}

Tailwind CSS v4

@theme {
  --color-dark-matter: #120506;
  --color-dark-matter-50: #fdf2f2;
  --color-dark-matter-100: #f0e5e5;
  --color-dark-matter-200: #dfd0d0;
  --color-dark-matter-300: #c4b2b3;
  --color-dark-matter-400: #ad9999;
  --color-dark-matter-500: #978081;
  --color-dark-matter-600: #7f6c6d;
  --color-dark-matter-700: #665657;
  --color-dark-matter-800: #4b3f40;
  --color-dark-matter-900: #342b2c;
  --color-dark-matter-950: #1f1919;
}

SCSS

$dark-matter: #120506;
$dark-matter-rgb: 18, 5, 6;
$dark-matter-light: mix(#fff, $dark-matter, 20%);
$dark-matter-dark: mix(#000, $dark-matter, 20%);

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