#182739

CSS

:root {
  --the-count-s-black: #182739;
  --the-count-s-black-rgb: 24 39 57;
  --the-count-s-black-oklch: oklch(0.268 0.04 253.6);
}

.element {
  color: var(--the-count-s-black);
  background-color: hsl(213 41% 16%);
  border-color: oklch(0.268 0.04 253.6);
}

Tailwind CSS v4

@theme {
  --color-the-count-s-black: #182739;
  --color-the-count-s-black-50: #eef6ff;
  --color-the-count-s-black-100: #dfe9f5;
  --color-the-count-s-black-200: #c9d5e5;
  --color-the-count-s-black-300: #aab9cc;
  --color-the-count-s-black-400: #8fa0b6;
  --color-the-count-s-black-500: #7488a0;
  --color-the-count-s-black-600: #637388;
  --color-the-count-s-black-700: #4f5c6d;
  --color-the-count-s-black-800: #394450;
  --color-the-count-s-black-900: #272f38;
  --color-the-count-s-black-950: #151b22;
}

SCSS

$the-count-s-black: #182739;
$the-count-s-black-rgb: 24, 39, 57;
$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);
}