#0F2C42

CSS

:root {
  --sea-of-stars: #0f2c42;
  --sea-of-stars-rgb: 15 44 66;
  --sea-of-stars-oklch: oklch(0.283 0.053 244.3);
}

.element {
  color: var(--sea-of-stars);
  background-color: hsl(206 63% 16%);
  border-color: oklch(0.283 0.053 244.3);
}

Tailwind CSS v4

@theme {
  --color-sea-of-stars: #0f2c42;
  --color-sea-of-stars-50: #e9f7ff;
  --color-sea-of-stars-100: #daeaf9;
  --color-sea-of-stars-200: #c2d7ea;
  --color-sea-of-stars-300: #a2bbd2;
  --color-sea-of-stars-400: #84a2bc;
  --color-sea-of-stars-500: #688aa7;
  --color-sea-of-stars-600: #58758e;
  --color-sea-of-stars-700: #465e71;
  --color-sea-of-stars-800: #324554;
  --color-sea-of-stars-900: #22303a;
  --color-sea-of-stars-950: #111c24;
}

SCSS

$sea-of-stars: #0f2c42;
$sea-of-stars-rgb: 15, 44, 66;
$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);
}