#003665

CSS

:root {
  --lost-in-space: #003665;
  --lost-in-space-rgb: 0 54 101;
  --lost-in-space-oklch: oklch(0.33 0.097 251.4);
}

.element {
  color: var(--lost-in-space);
  background-color: hsl(208 100% 20%);
  border-color: oklch(0.33 0.097 251.4);
}

Tailwind CSS v4

@theme {
  --color-lost-in-space: #003665;
  --color-lost-in-space-50: #e2f7ff;
  --color-lost-in-space-100: #d2ebff;
  --color-lost-in-space-200: #b8d7fe;
  --color-lost-in-space-300: #95bbe9;
  --color-lost-in-space-400: #73a2d6;
  --color-lost-in-space-500: #538ac5;
  --color-lost-in-space-600: #4775a6;
  --color-lost-in-space-700: #385d85;
  --color-lost-in-space-800: #264563;
  --color-lost-in-space-900: #1a3045;
  --color-lost-in-space-950: #0a1c2d;
}

SCSS

$lost-in-space: #003665;
$lost-in-space-rgb: 0, 54, 101;
$lost-in-space-light: mix(#fff, $lost-in-space, 20%);
$lost-in-space-dark: mix(#000, $lost-in-space, 20%);

.element {
  color: $lost-in-space;
  box-shadow: 0 0 0 2px rgba($lost-in-space, 0.35);
}