#031318

CSS

:root {
  --black-stallion: #031318;
  --black-stallion-rgb: 3 19 24;
  --black-stallion-oklch: oklch(0.175 0.026 219);
}

.element {
  color: var(--black-stallion);
  background-color: hsl(194 78% 5%);
  border-color: oklch(0.175 0.026 219);
}

Tailwind CSS v4

@theme {
  --color-black-stallion: #031318;
  --color-black-stallion-50: #eef7fa;
  --color-black-stallion-100: #dfeaee;
  --color-black-stallion-200: #c9d7dc;
  --color-black-stallion-300: #aabbc1;
  --color-black-stallion-400: #8ea2a9;
  --color-black-stallion-500: #748b92;
  --color-black-stallion-600: #62757b;
  --color-black-stallion-700: #4e5e63;
  --color-black-stallion-800: #394548;
  --color-black-stallion-900: #273032;
  --color-black-stallion-950: #151c1e;
}

SCSS

$black-stallion: #031318;
$black-stallion-rgb: 3, 19, 24;
$black-stallion-light: mix(#fff, $black-stallion, 20%);
$black-stallion-dark: mix(#000, $black-stallion, 20%);

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