#0A1923

CSS

:root {
  --the-count-s-black: #0a1923;
  --the-count-s-black-rgb: 10 25 35;
  --the-count-s-black-oklch: oklch(0.205 0.029 239.4);
}

.element {
  color: var(--the-count-s-black);
  background-color: hsl(204 56% 9%);
  border-color: oklch(0.205 0.029 239.4);
}

Tailwind CSS v4

@theme {
  --color-the-count-s-black: #0a1923;
  --color-the-count-s-black-50: #eef6fd;
  --color-the-count-s-black-100: #e0e9f1;
  --color-the-count-s-black-200: #cad6e0;
  --color-the-count-s-black-300: #abbac5;
  --color-the-count-s-black-400: #90a1ae;
  --color-the-count-s-black-500: #758998;
  --color-the-count-s-black-600: #637480;
  --color-the-count-s-black-700: #4f5d67;
  --color-the-count-s-black-800: #39444b;
  --color-the-count-s-black-900: #272f34;
  --color-the-count-s-black-950: #151c20;
}

SCSS

$the-count-s-black: #0a1923;
$the-count-s-black-rgb: 10, 25, 35;
$the-count-s-black-light: mix(#fff, $the-count-s-black, 20%);
$the-count-s-black-dark: mix(#000, $the-count-s-black, 20%);

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