#010063

CSS

:root {
  --alone-in-the-dark: #010063;
  --alone-in-the-dark-rgb: 1 0 99;
  --alone-in-the-dark-oklch: oklch(0.226 0.156 264.6);
}

.element {
  color: var(--alone-in-the-dark);
  background-color: hsl(241 100% 19%);
  border-color: oklch(0.226 0.156 264.6);
}

Tailwind CSS v4

@theme {
  --color-alone-in-the-dark: #010063;
  --color-alone-in-the-dark-50: #e1f5ff;
  --color-alone-in-the-dark-100: #d0e7ff;
  --color-alone-in-the-dark-200: #b6d3ff;
  --color-alone-in-the-dark-300: #93b5ff;
  --color-alone-in-the-dark-400: #709bfa;
  --color-alone-in-the-dark-500: #517fec;
  --color-alone-in-the-dark-600: #456cc7;
  --color-alone-in-the-dark-700: #3757a0;
  --color-alone-in-the-dark-800: #244078;
  --color-alone-in-the-dark-900: #182c54;
  --color-alone-in-the-dark-950: #091939;
}

SCSS

$alone-in-the-dark: #010063;
$alone-in-the-dark-rgb: 1, 0, 99;
$alone-in-the-dark-light: mix(#fff, $alone-in-the-dark, 20%);
$alone-in-the-dark-dark: mix(#000, $alone-in-the-dark, 20%);

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