#04090F

CSS

:root {
  --eight-ball: #04090f;
  --eight-ball-rgb: 4 9 15;
  --eight-ball-oklch: oklch(0.136 0.017 247);
}

.element {
  color: var(--eight-ball);
  background-color: hsl(213 58% 4%);
  border-color: oklch(0.136 0.017 247);
}

Tailwind CSS v4

@theme {
  --color-eight-ball: #04090f;
  --color-eight-ball-50: #f1f6fa;
  --color-eight-ball-100: #e4e8ed;
  --color-eight-ball-200: #cfd5db;
  --color-eight-ball-300: #b1b8c0;
  --color-eight-ball-400: #97a0a8;
  --color-eight-ball-500: #7d8791;
  --color-eight-ball-600: #6a737b;
  --color-eight-ball-700: #555c62;
  --color-eight-ball-800: #3e4348;
  --color-eight-ball-900: #2a2e32;
  --color-eight-ball-950: #181b1e;
}

SCSS

$eight-ball: #04090f;
$eight-ball-rgb: 4, 9, 15;
$eight-ball-light: mix(#fff, $eight-ball, 20%);
$eight-ball-dark: mix(#000, $eight-ball, 20%);

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