#140809

CSS

:root {
  --dark-matter: #140809;
  --dark-matter-rgb: 20 8 9;
  --dark-matter-oklch: oklch(0.153 0.022 14.1);
}

.element {
  color: var(--dark-matter);
  background-color: hsl(355 43% 5%);
  border-color: oklch(0.153 0.022 14.1);
}

Tailwind CSS v4

@theme {
  --color-dark-matter: #140809;
  --color-dark-matter-50: #fbf3f3;
  --color-dark-matter-100: #efe5e5;
  --color-dark-matter-200: #ddd1d1;
  --color-dark-matter-300: #c2b3b3;
  --color-dark-matter-400: #ab999a;
  --color-dark-matter-500: #948182;
  --color-dark-matter-600: #7d6d6e;
  --color-dark-matter-700: #645758;
  --color-dark-matter-800: #4a3f40;
  --color-dark-matter-900: #332c2c;
  --color-dark-matter-950: #1f1919;
}

SCSS

$dark-matter: #140809;
$dark-matter-rgb: 20, 8, 9;
$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);
}