#3F70DA

CSS

:root {
  --skies-of-cyberspace: #3f70da;
  --skies-of-cyberspace-rgb: 63 112 218;
  --skies-of-cyberspace-oklch: oklch(0.568 0.171 263.3);
}

.element {
  color: var(--skies-of-cyberspace);
  background-color: hsl(221 68% 55%);
  border-color: oklch(0.568 0.171 263.3);
}

Tailwind CSS v4

@theme {
  --color-skies-of-cyberspace: #3f70da;
  --color-skies-of-cyberspace-50: #def5ff;
  --color-skies-of-cyberspace-100: #cce8ff;
  --color-skies-of-cyberspace-200: #b1d3ff;
  --color-skies-of-cyberspace-300: #8db5ff;
  --color-skies-of-cyberspace-400: #689aff;
  --color-skies-of-cyberspace-500: #477ef6;
  --color-skies-of-cyberspace-600: #3d6bcf;
  --color-skies-of-cyberspace-700: #3056a7;
  --color-skies-of-cyberspace-800: #1e3f7d;
  --color-skies-of-cyberspace-900: #142c58;
  --color-skies-of-cyberspace-950: #06183c;
}

SCSS

$skies-of-cyberspace: #3f70da;
$skies-of-cyberspace-rgb: 63, 112, 218;
$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);
}