#2F78CA

CSS

:root {
  --fading-night: #2f78ca;
  --fading-night-rgb: 47 120 202;
  --fading-night-oklch: oklch(0.569 0.146 253.9);
}

.element {
  color: var(--fading-night);
  background-color: hsl(212 62% 49%);
  border-color: oklch(0.569 0.146 253.9);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #2f78ca;
  --color-fading-night-50: #daf8ff;
  --color-fading-night-100: #c8ebff;
  --color-fading-night-200: #abd7ff;
  --color-fading-night-300: #85baff;
  --color-fading-night-400: #5da1f2;
  --color-fading-night-500: #3587e3;
  --color-fading-night-600: #2e73c0;
  --color-fading-night-700: #255c9a;
  --color-fading-night-800: #154473;
  --color-fading-night-900: #0d2f51;
  --color-fading-night-950: #021b36;
}

SCSS

$fading-night: #2f78ca;
$fading-night-rgb: 47, 120, 202;
$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);
}