#5173CB

CSS

:root {
  --skies-of-cyberspace: #5173cb;
  --skies-of-cyberspace-rgb: 81 115 203;
  --skies-of-cyberspace-oklch: oklch(0.573 0.141 266.2);
}

.element {
  color: var(--skies-of-cyberspace);
  background-color: hsl(223 54% 56%);
  border-color: oklch(0.573 0.141 266.2);
}

Tailwind CSS v4

@theme {
  --color-skies-of-cyberspace: #5173cb;
  --color-skies-of-cyberspace-50: #e4f5ff;
  --color-skies-of-cyberspace-100: #d4e7ff;
  --color-skies-of-cyberspace-200: #bad3ff;
  --color-skies-of-cyberspace-300: #99b5ff;
  --color-skies-of-cyberspace-400: #779bf2;
  --color-skies-of-cyberspace-500: #5a80e3;
  --color-skies-of-cyberspace-600: #4d6dbf;
  --color-skies-of-cyberspace-700: #3d579a;
  --color-skies-of-cyberspace-800: #294073;
  --color-skies-of-cyberspace-900: #1b2c51;
  --color-skies-of-cyberspace-950: #0c1936;
}

SCSS

$skies-of-cyberspace: #5173cb;
$skies-of-cyberspace-rgb: 81, 115, 203;
$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);
}