#4E71C7

CSS

:root {
  --skies-of-cyberspace: #4e71c7;
  --skies-of-cyberspace-rgb: 78 113 199;
  --skies-of-cyberspace-oklch: oklch(0.565 0.139 265.5);
}

.element {
  color: var(--skies-of-cyberspace);
  background-color: hsl(223 52% 54%);
  border-color: oklch(0.565 0.139 265.5);
}

Tailwind CSS v4

@theme {
  --color-skies-of-cyberspace: #4e71c7;
  --color-skies-of-cyberspace-50: #e4f5ff;
  --color-skies-of-cyberspace-100: #d3e7ff;
  --color-skies-of-cyberspace-200: #bad3ff;
  --color-skies-of-cyberspace-300: #98b5ff;
  --color-skies-of-cyberspace-400: #779bf1;
  --color-skies-of-cyberspace-500: #5981e2;
  --color-skies-of-cyberspace-600: #4c6dbe;
  --color-skies-of-cyberspace-700: #3c5799;
  --color-skies-of-cyberspace-800: #294072;
  --color-skies-of-cyberspace-900: #1b2c50;
  --color-skies-of-cyberspace-950: #0c1936;
}

SCSS

$skies-of-cyberspace: #4e71c7;
$skies-of-cyberspace-rgb: 78, 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);
}