#04040A

CSS

:root {
  --eight-ball: #04040a;
  --eight-ball-rgb: 4 4 10;
  --eight-ball-oklch: oklch(0.111 0.018 283.2);
}

.element {
  color: var(--eight-ball);
  background-color: hsl(240 43% 3%);
  border-color: oklch(0.111 0.018 283.2);
}

Tailwind CSS v4

@theme {
  --color-eight-ball: #04040a;
  --color-eight-ball-50: #f4f4fa;
  --color-eight-ball-100: #e7e7ee;
  --color-eight-ball-200: #d3d3dc;
  --color-eight-ball-300: #b6b6c0;
  --color-eight-ball-400: #9d9da9;
  --color-eight-ball-500: #848592;
  --color-eight-ball-600: #70707b;
  --color-eight-ball-700: #595a63;
  --color-eight-ball-800: #414248;
  --color-eight-ball-900: #2d2d32;
  --color-eight-ball-950: #1a1a1e;
}

SCSS

$eight-ball: #04040a;
$eight-ball-rgb: 4, 4, 10;
$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);
}