#2F76C3

CSS

:root {
  --fading-night: #2f76c3;
  --fading-night-rgb: 47 118 195;
  --fading-night-oklch: oklch(0.56 0.139 253.1);
}

.element {
  color: var(--fading-night);
  background-color: hsl(211 61% 47%);
  border-color: oklch(0.56 0.139 253.1);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #2f76c3;
  --color-fading-night-50: #dbf8ff;
  --color-fading-night-100: #c9ebff;
  --color-fading-night-200: #add8ff;
  --color-fading-night-300: #86bafd;
  --color-fading-night-400: #5fa2ee;
  --color-fading-night-500: #3888df;
  --color-fading-night-600: #3173bc;
  --color-fading-night-700: #275c97;
  --color-fading-night-800: #174470;
  --color-fading-night-900: #0f2f4f;
  --color-fading-night-950: #021b35;
}

SCSS

$fading-night: #2f76c3;
$fading-night-rgb: 47, 118, 195;
$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);
}