#003861

CSS

:root {
  --lost-in-space: #003861;
  --lost-in-space-rgb: 0 56 97;
  --lost-in-space-oklch: oklch(0.332 0.089 247.9);
}

.element {
  color: var(--lost-in-space);
  background-color: hsl(205 100% 19%);
  border-color: oklch(0.332 0.089 247.9);
}

Tailwind CSS v4

@theme {
  --color-lost-in-space: #003861;
  --color-lost-in-space-50: #e3f8ff;
  --color-lost-in-space-100: #d2ebff;
  --color-lost-in-space-200: #b8d8fa;
  --color-lost-in-space-300: #95bce4;
  --color-lost-in-space-400: #73a3d1;
  --color-lost-in-space-500: #538bbe;
  --color-lost-in-space-600: #4776a1;
  --color-lost-in-space-700: #395e81;
  --color-lost-in-space-800: #27455f;
  --color-lost-in-space-900: #1a3043;
  --color-lost-in-space-950: #0a1c2b;
}

SCSS

$lost-in-space: #003861;
$lost-in-space-rgb: 0, 56, 97;
$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);
}