#2976D6

CSS

:root {
  --fading-night: #2976d6;
  --fading-night-rgb: 41 118 214;
  --fading-night-oklch: oklch(0.571 0.165 256.1);
}

.element {
  color: var(--fading-night);
  background-color: hsl(213 68% 50%);
  border-color: oklch(0.571 0.165 256.1);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #2976d6;
  --color-fading-night-50: #d8f7ff;
  --color-fading-night-100: #c6eaff;
  --color-fading-night-200: #a8d6ff;
  --color-fading-night-300: #81b9ff;
  --color-fading-night-400: #589ffe;
  --color-fading-night-500: #2d84f0;
  --color-fading-night-600: #2870ca;
  --color-fading-night-700: #205aa3;
  --color-fading-night-800: #104279;
  --color-fading-night-900: #0a2e56;
  --color-fading-night-950: #001a3a;
}

SCSS

$fading-night: #2976d6;
$fading-night-rgb: 41, 118, 214;
$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);
}