#00464B

CSS

:root {
  --rich-black: #00464b;
  --rich-black-rgb: 0 70 75;
  --rich-black-oklch: oklch(0.359 0.061 202.9);
}

.element {
  color: var(--rich-black);
  background-color: hsl(184 100% 15%);
  border-color: oklch(0.359 0.061 202.9);
}

Tailwind CSS v4

@theme {
  --color-rich-black: #00464b;
  --color-rich-black-50: #e2fbfd;
  --color-rich-black-100: #d1eef2;
  --color-rich-black-200: #b7dce1;
  --color-rich-black-300: #93c1c6;
  --color-rich-black-400: #72aaae;
  --color-rich-black-500: #519298;
  --color-rich-black-600: #467c81;
  --color-rich-black-700: #376367;
  --color-rich-black-800: #27494b;
  --color-rich-black-900: #1a3334;
  --color-rich-black-950: #0a1e20;
}

SCSS

$rich-black: #00464b;
$rich-black-rgb: 0, 70, 75;
$rich-black-light: mix(#fff, $rich-black, 20%);
$rich-black-dark: mix(#000, $rich-black, 20%);

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