#3C73CD

CSS

:root {
  --fading-night: #3c73cd;
  --fading-night-rgb: 60 115 205;
  --fading-night-oklch: oklch(0.564 0.151 259.8);
}

.element {
  color: var(--fading-night);
  background-color: hsl(217 59% 52%);
  border-color: oklch(0.564 0.151 259.8);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #3c73cd;
  --color-fading-night-50: #def6ff;
  --color-fading-night-100: #cce9ff;
  --color-fading-night-200: #b1d5ff;
  --color-fading-night-300: #8cb7ff;
  --color-fading-night-400: #679ef7;
  --color-fading-night-500: #4583e8;
  --color-fading-night-600: #3b6fc4;
  --color-fading-night-700: #2f599e;
  --color-fading-night-800: #1d4276;
  --color-fading-night-900: #132d53;
  --color-fading-night-950: #051a38;
}

SCSS

$fading-night: #3c73cd;
$fading-night-rgb: 60, 115, 205;
$fading-night-light: mix(#fff, $fading-night, 20%);
$fading-night-dark: mix(#000, $fading-night, 20%);

.element {
  color: $fading-night;
  box-shadow: 0 0 0 2px rgba($fading-night, 0.35);
}