#3F73CD

CSS

:root {
  --skies-of-cyberspace: #3f73cd;
  --skies-of-cyberspace-rgb: 63 115 205;
  --skies-of-cyberspace-oklch: oklch(0.566 0.15 260.6);
}

.element {
  color: var(--skies-of-cyberspace);
  background-color: hsl(218 59% 53%);
  border-color: oklch(0.566 0.15 260.6);
}

Tailwind CSS v4

@theme {
  --color-skies-of-cyberspace: #3f73cd;
  --color-skies-of-cyberspace-50: #def6ff;
  --color-skies-of-cyberspace-100: #cde9ff;
  --color-skies-of-cyberspace-200: #b2d5ff;
  --color-skies-of-cyberspace-300: #8eb7ff;
  --color-skies-of-cyberspace-400: #699df6;
  --color-skies-of-cyberspace-500: #4883e8;
  --color-skies-of-cyberspace-600: #3e6fc4;
  --color-skies-of-cyberspace-700: #31599d;
  --color-skies-of-cyberspace-800: #1f4175;
  --color-skies-of-cyberspace-900: #142d53;
  --color-skies-of-cyberspace-950: #061a38;
}

SCSS

$skies-of-cyberspace: #3f73cd;
$skies-of-cyberspace-rgb: 63, 115, 205;
$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);
}