#150914

CSS

:root {
  --noir-fiction: #150914;
  --noir-fiction-rgb: 21 9 20;
  --noir-fiction-oklch: oklch(0.163 0.03 329.8);
}

.element {
  color: var(--noir-fiction);
  background-color: hsl(305 40% 6%);
  border-color: oklch(0.163 0.03 329.8);
}

Tailwind CSS v4

@theme {
  --color-noir-fiction: #150914;
  --color-noir-fiction-50: #fbf2f9;
  --color-noir-fiction-100: #eee4ec;
  --color-noir-fiction-200: #dcd0da;
  --color-noir-fiction-300: #c1b2be;
  --color-noir-fiction-400: #a998a7;
  --color-noir-fiction-500: #927f90;
  --color-noir-fiction-600: #7b6c7a;
  --color-noir-fiction-700: #635661;
  --color-noir-fiction-800: #483f48;
  --color-noir-fiction-900: #322b32;
  --color-noir-fiction-950: #1e191e;
}

SCSS

$noir-fiction: #150914;
$noir-fiction-rgb: 21, 9, 20;
$noir-fiction-light: mix(#fff, $noir-fiction, 20%);
$noir-fiction-dark: mix(#000, $noir-fiction, 20%);

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