#14121C

CSS

:root {
  --back-in-black: #14121c;
  --back-in-black-rgb: 20 18 28;
  --back-in-black-oklch: oklch(0.19 0.02 293.5);
}

.element {
  color: var(--back-in-black);
  background-color: hsl(252 22% 9%);
  border-color: oklch(0.19 0.02 293.5);
}

Tailwind CSS v4

@theme {
  --color-back-in-black: #14121c;
  --color-back-in-black-50: #f5f4fa;
  --color-back-in-black-100: #e8e7ee;
  --color-back-in-black-200: #d5d3dc;
  --color-back-in-black-300: #b8b5c1;
  --color-back-in-black-400: #9f9caa;
  --color-back-in-black-500: #868493;
  --color-back-in-black-600: #72707c;
  --color-back-in-black-700: #5b5963;
  --color-back-in-black-800: #424149;
  --color-back-in-black-900: #2e2d33;
  --color-back-in-black-950: #1a1a1e;
}

SCSS

$back-in-black: #14121c;
$back-in-black-rgb: 20, 18, 28;
$back-in-black-light: mix(#fff, $back-in-black, 20%);
$back-in-black-dark: mix(#000, $back-in-black, 20%);

.element {
  color: $back-in-black;
  box-shadow: 0 0 0 2px rgba($back-in-black, 0.35);
}