#020F4E

CSS

:root {
  --interstellar-blue: #020f4e;
  --interstellar-blue-rgb: 2 15 78;
  --interstellar-blue-oklch: oklch(0.218 0.115 264.8);
}

.element {
  color: var(--interstellar-blue);
  background-color: hsl(230 95% 16%);
  border-color: oklch(0.218 0.115 264.8);
}

Tailwind CSS v4

@theme {
  --color-interstellar-blue: #020f4e;
  --color-interstellar-blue-50: #e6f5ff;
  --color-interstellar-blue-100: #d6e8ff;
  --color-interstellar-blue-200: #bed4ff;
  --color-interstellar-blue-300: #9db6f3;
  --color-interstellar-blue-400: #7d9de3;
  --color-interstellar-blue-500: #6083d2;
  --color-interstellar-blue-600: #526fb2;
  --color-interstellar-blue-700: #41598f;
  --color-interstellar-blue-800: #2d416a;
  --color-interstellar-blue-900: #1e2d4b;
  --color-interstellar-blue-950: #0e1a31;
}

SCSS

$interstellar-blue: #020f4e;
$interstellar-blue-rgb: 2, 15, 78;
$interstellar-blue-light: mix(#fff, $interstellar-blue, 20%);
$interstellar-blue-dark: mix(#000, $interstellar-blue, 20%);

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