#2B76C8

CSS

:root {
  --fading-night: #2b76c8;
  --fading-night-rgb: 43 118 200;
  --fading-night-oklch: oklch(0.562 0.146 253.6);
}

.element {
  color: var(--fading-night);
  background-color: hsl(211 65% 48%);
  border-color: oklch(0.562 0.146 253.6);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #2b76c8;
  --color-fading-night-50: #daf8ff;
  --color-fading-night-100: #c8ebff;
  --color-fading-night-200: #abd7ff;
  --color-fading-night-300: #84baff;
  --color-fading-night-400: #5ca1f2;
  --color-fading-night-500: #3387e4;
  --color-fading-night-600: #2d73c0;
  --color-fading-night-700: #245c9a;
  --color-fading-night-800: #144473;
  --color-fading-night-900: #0d2f51;
  --color-fading-night-950: #011b36;
}

SCSS

$fading-night: #2b76c8;
$fading-night-rgb: 43, 118, 200;
$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);
}