#120311

CSS

:root {
  --glossy-black: #120311;
  --glossy-black-rgb: 18 3 17;
  --glossy-black-oklch: oklch(0.138 0.043 329.9);
}

.element {
  color: var(--glossy-black);
  background-color: hsl(304 71% 4%);
  border-color: oklch(0.138 0.043 329.9);
}

Tailwind CSS v4

@theme {
  --color-glossy-black: #120311;
  --color-glossy-black-50: #fdf1fb;
  --color-glossy-black-100: #f1e3ee;
  --color-glossy-black-200: #e0cedd;
  --color-glossy-black-300: #c5b0c1;
  --color-glossy-black-400: #ae96ab;
  --color-glossy-black-500: #977c94;
  --color-glossy-black-600: #80697d;
  --color-glossy-black-700: #665464;
  --color-glossy-black-800: #4b3d4a;
  --color-glossy-black-900: #342a33;
  --color-glossy-black-950: #1f181f;
}

SCSS

$glossy-black: #120311;
$glossy-black-rgb: 18, 3, 17;
$glossy-black-light: mix(#fff, $glossy-black, 20%);
$glossy-black-dark: mix(#000, $glossy-black, 20%);

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