#110B14

CSS

:root {
  --back-in-black: #110b14;
  --back-in-black-rgb: 17 11 20;
  --back-in-black-oklch: oklch(0.162 0.021 314.2);
}

.element {
  color: var(--back-in-black);
  background-color: hsl(280 29% 6%);
  border-color: oklch(0.162 0.021 314.2);
}

Tailwind CSS v4

@theme {
  --color-back-in-black: #110b14;
  --color-back-in-black-50: #f7f3f9;
  --color-back-in-black-100: #ebe6ed;
  --color-back-in-black-200: #d8d2da;
  --color-back-in-black-300: #bcb4bf;
  --color-back-in-black-400: #a39ba7;
  --color-back-in-black-500: #8b8290;
  --color-back-in-black-600: #766e7a;
  --color-back-in-black-700: #5e5861;
  --color-back-in-black-800: #454048;
  --color-back-in-black-900: #302c32;
  --color-back-in-black-950: #1c191e;
}

SCSS

$back-in-black: #110b14;
$back-in-black-rgb: 17, 11, 20;
$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);
}