#000E14

CSS

:root {
  --black-knight: #000e14;
  --black-knight-rgb: 0 14 20;
  --black-knight-oklch: oklch(0.152 0.028 222.2);
}

.element {
  color: var(--black-knight);
  background-color: hsl(198 100% 4%);
  border-color: oklch(0.152 0.028 222.2);
}

Tailwind CSS v4

@theme {
  --color-black-knight: #000e14;
  --color-black-knight-50: #edf7fb;
  --color-black-knight-100: #deeaef;
  --color-black-knight-200: #c8d7dd;
  --color-black-knight-300: #a9bbc2;
  --color-black-knight-400: #8da3aa;
  --color-black-knight-500: #728b94;
  --color-black-knight-600: #61757d;
  --color-black-knight-700: #4d5e64;
  --color-black-knight-800: #384549;
  --color-black-knight-900: #263033;
  --color-black-knight-950: #151c1e;
}

SCSS

$black-knight: #000e14;
$black-knight-rgb: 0, 14, 20;
$black-knight-light: mix(#fff, $black-knight, 20%);
$black-knight-dark: mix(#000, $black-knight, 20%);

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