#0A1C2A

CSS

:root {
  --the-count-s-black: #0a1c2a;
  --the-count-s-black-rgb: 10 28 42;
  --the-count-s-black-oklch: oklch(0.219 0.037 244.1);
}

.element {
  color: var(--the-count-s-black);
  background-color: hsl(206 62% 10%);
  border-color: oklch(0.219 0.037 244.1);
}

Tailwind CSS v4

@theme {
  --color-the-count-s-black: #0a1c2a;
  --color-the-count-s-black-50: #edf6ff;
  --color-the-count-s-black-100: #dee9f4;
  --color-the-count-s-black-200: #c8d6e3;
  --color-the-count-s-black-300: #a9bac9;
  --color-the-count-s-black-400: #8da1b3;
  --color-the-count-s-black-500: #72899d;
  --color-the-count-s-black-600: #617485;
  --color-the-count-s-black-700: #4d5d6a;
  --color-the-count-s-black-800: #37444e;
  --color-the-count-s-black-900: #262f36;
  --color-the-count-s-black-950: #141c21;
}

SCSS

$the-count-s-black: #0a1c2a;
$the-count-s-black-rgb: 10, 28, 42;
$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);
}