#5171C7

CSS

:root {
  --skies-of-cyberspace: #5171c7;
  --skies-of-cyberspace-rgb: 81 113 199;
  --skies-of-cyberspace-oklch: oklch(0.566 0.138 266.7);
}

.element {
  color: var(--skies-of-cyberspace);
  background-color: hsl(224 51% 55%);
  border-color: oklch(0.566 0.138 266.7);
}

Tailwind CSS v4

@theme {
  --color-skies-of-cyberspace: #5171c7;
  --color-skies-of-cyberspace-50: #e5f5ff;
  --color-skies-of-cyberspace-100: #d5e7ff;
  --color-skies-of-cyberspace-200: #bcd3ff;
  --color-skies-of-cyberspace-300: #9ab4ff;
  --color-skies-of-cyberspace-400: #799bf0;
  --color-skies-of-cyberspace-500: #5c80e1;
  --color-skies-of-cyberspace-600: #4e6dbe;
  --color-skies-of-cyberspace-700: #3e5798;
  --color-skies-of-cyberspace-800: #2a4072;
  --color-skies-of-cyberspace-900: #1c2c50;
  --color-skies-of-cyberspace-950: #0d1936;
}

SCSS

$skies-of-cyberspace: #5171c7;
$skies-of-cyberspace-rgb: 81, 113, 199;
$skies-of-cyberspace-light: mix(#fff, $skies-of-cyberspace, 20%);
$skies-of-cyberspace-dark: mix(#000, $skies-of-cyberspace, 20%);

.element {
  color: $skies-of-cyberspace;
  box-shadow: 0 0 0 2px rgba($skies-of-cyberspace, 0.35);
}