#002B41

CSS

:root {
  --sea-of-stars: #002b41;
  --sea-of-stars-rgb: 0 43 65;
  --sea-of-stars-oklch: oklch(0.274 0.06 237.3);
}

.element {
  color: var(--sea-of-stars);
  background-color: hsl(200 100% 13%);
  border-color: oklch(0.274 0.06 237.3);
}

Tailwind CSS v4

@theme {
  --color-sea-of-stars: #002b41;
  --color-sea-of-stars-50: #e6f8ff;
  --color-sea-of-stars-100: #d7ebfa;
  --color-sea-of-stars-200: #bed8ec;
  --color-sea-of-stars-300: #9cbcd3;
  --color-sea-of-stars-400: #7da4be;
  --color-sea-of-stars-500: #5f8ca9;
  --color-sea-of-stars-600: #51778f;
  --color-sea-of-stars-700: #405f73;
  --color-sea-of-stars-800: #2d4654;
  --color-sea-of-stars-900: #1f303b;
  --color-sea-of-stars-950: #0e1d25;
}

SCSS

$sea-of-stars: #002b41;
$sea-of-stars-rgb: 0, 43, 65;
$sea-of-stars-light: mix(#fff, $sea-of-stars, 20%);
$sea-of-stars-dark: mix(#000, $sea-of-stars, 20%);

.element {
  color: $sea-of-stars;
  box-shadow: 0 0 0 2px rgba($sea-of-stars, 0.35);
}