#0D1825

CSS

:root {
  --the-count-s-black: #0d1825;
  --the-count-s-black-rgb: 13 24 37;
  --the-count-s-black-oklch: oklch(0.206 0.031 253.3);
}

.element {
  color: var(--the-count-s-black);
  background-color: hsl(213 48% 10%);
  border-color: oklch(0.206 0.031 253.3);
}

Tailwind CSS v4

@theme {
  --color-the-count-s-black: #0d1825;
  --color-the-count-s-black-50: #eff6fe;
  --color-the-count-s-black-100: #e1e9f2;
  --color-the-count-s-black-200: #ccd5e2;
  --color-the-count-s-black-300: #adb8c7;
  --color-the-count-s-black-400: #92a0b1;
  --color-the-count-s-black-500: #78889b;
  --color-the-count-s-black-600: #667383;
  --color-the-count-s-black-700: #515c69;
  --color-the-count-s-black-800: #3b434d;
  --color-the-count-s-black-900: #282e35;
  --color-the-count-s-black-950: #161b21;
}

SCSS

$the-count-s-black: #0d1825;
$the-count-s-black-rgb: 13, 24, 37;
$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);
}