#03141A

CSS

:root {
  --black-stallion: #03141a;
  --black-stallion-rgb: 3 20 26;
  --black-stallion-oklch: oklch(0.179 0.027 222);
}

.element {
  color: var(--black-stallion);
  background-color: hsl(196 79% 6%);
  border-color: oklch(0.179 0.027 222);
}

Tailwind CSS v4

@theme {
  --color-black-stallion: #03141a;
  --color-black-stallion-50: #edf7fb;
  --color-black-stallion-100: #dfeaef;
  --color-black-stallion-200: #c8d7dd;
  --color-black-stallion-300: #a9bbc2;
  --color-black-stallion-400: #8ea2aa;
  --color-black-stallion-500: #738b93;
  --color-black-stallion-600: #61757d;
  --color-black-stallion-700: #4e5e64;
  --color-black-stallion-800: #384549;
  --color-black-stallion-900: #263033;
  --color-black-stallion-950: #151c1e;
}

SCSS

$black-stallion: #03141a;
$black-stallion-rgb: 3, 20, 26;
$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);
}