#3F72D1

CSS

:root {
  --skies-of-cyberspace: #3f72d1;
  --skies-of-cyberspace-rgb: 63 114 209;
  --skies-of-cyberspace-oklch: oklch(0.566 0.157 261.6);
}

.element {
  color: var(--skies-of-cyberspace);
  background-color: hsl(219 61% 53%);
  border-color: oklch(0.566 0.157 261.6);
}

Tailwind CSS v4

@theme {
  --color-skies-of-cyberspace: #3f72d1;
  --color-skies-of-cyberspace-50: #def6ff;
  --color-skies-of-cyberspace-100: #cde8ff;
  --color-skies-of-cyberspace-200: #b2d4ff;
  --color-skies-of-cyberspace-300: #8eb6ff;
  --color-skies-of-cyberspace-400: #699cfa;
  --color-skies-of-cyberspace-500: #4881ec;
  --color-skies-of-cyberspace-600: #3e6ec7;
  --color-skies-of-cyberspace-700: #3158a0;
  --color-skies-of-cyberspace-800: #1f4178;
  --color-skies-of-cyberspace-900: #142d54;
  --color-skies-of-cyberspace-950: #061939;
}

SCSS

$skies-of-cyberspace: #3f72d1;
$skies-of-cyberspace-rgb: 63, 114, 209;
$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);
}