#0A1927

CSS

:root {
  --the-count-s-black: #0a1927;
  --the-count-s-black-rgb: 10 25 39;
  --the-count-s-black-oklch: oklch(0.208 0.035 248.3);
}

.element {
  color: var(--the-count-s-black);
  background-color: hsl(209 59% 10%);
  border-color: oklch(0.208 0.035 248.3);
}

Tailwind CSS v4

@theme {
  --color-the-count-s-black: #0a1927;
  --color-the-count-s-black-50: #eef6ff;
  --color-the-count-s-black-100: #e0e9f3;
  --color-the-count-s-black-200: #cad6e3;
  --color-the-count-s-black-300: #abb9c9;
  --color-the-count-s-black-400: #8fa1b3;
  --color-the-count-s-black-500: #74899d;
  --color-the-count-s-black-600: #637484;
  --color-the-count-s-black-700: #4f5c6a;
  --color-the-count-s-black-800: #39444e;
  --color-the-count-s-black-900: #272f36;
  --color-the-count-s-black-950: #151b21;
}

SCSS

$the-count-s-black: #0a1927;
$the-count-s-black-rgb: 10, 25, 39;
$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);
}