#020D14

CSS

:root {
  --black-knight: #020d14;
  --black-knight-rgb: 2 13 20;
  --black-knight-oklch: oklch(0.151 0.025 232.5);
}

.element {
  color: var(--black-knight);
  background-color: hsl(203 82% 4%);
  border-color: oklch(0.151 0.025 232.5);
}

Tailwind CSS v4

@theme {
  --color-black-knight: #020d14;
  --color-black-knight-50: #eff6fb;
  --color-black-knight-100: #e0e9ef;
  --color-black-knight-200: #cbd6dd;
  --color-black-knight-300: #acbac2;
  --color-black-knight-400: #91a1ab;
  --color-black-knight-500: #768994;
  --color-black-knight-600: #64747d;
  --color-black-knight-700: #505d64;
  --color-black-knight-800: #3a4449;
  --color-black-knight-900: #282f33;
  --color-black-knight-950: #161c1f;
}

SCSS

$black-knight: #020d14;
$black-knight-rgb: 2, 13, 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);
}