#03080A

CSS

:root {
  --black-hole: #03080a;
  --black-hole-rgb: 3 8 10;
  --black-hole-oklch: oklch(0.128 0.013 218.2);
}

.element {
  color: var(--black-hole);
  background-color: hsl(197 54% 3%);
  border-color: oklch(0.128 0.013 218.2);
}

Tailwind CSS v4

@theme {
  --color-black-hole: #03080a;
  --color-black-hole-50: #f1f6f8;
  --color-black-hole-100: #e4e9eb;
  --color-black-hole-200: #cfd6d8;
  --color-black-hole-300: #b1b9bc;
  --color-black-hole-400: #97a0a3;
  --color-black-hole-500: #7d888c;
  --color-black-hole-600: #6a7376;
  --color-black-hole-700: #555c5f;
  --color-black-hole-800: #3e4345;
  --color-black-hole-900: #2a2f30;
  --color-black-hole-950: #181b1c;
}

SCSS

$black-hole: #03080a;
$black-hole-rgb: 3, 8, 10;
$black-hole-light: mix(#fff, $black-hole, 20%);
$black-hole-dark: mix(#000, $black-hole, 20%);

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