#2D76C4

CSS

:root {
  --fading-night: #2d76c4;
  --fading-night-rgb: 45 118 196;
  --fading-night-oklch: oklch(0.56 0.141 253);
}

.element {
  color: var(--fading-night);
  background-color: hsl(211 63% 47%);
  border-color: oklch(0.56 0.141 253);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #2d76c4;
  --color-fading-night-50: #dbf8ff;
  --color-fading-night-100: #c9ebff;
  --color-fading-night-200: #acd8ff;
  --color-fading-night-300: #85bbfe;
  --color-fading-night-400: #5ea2ef;
  --color-fading-night-500: #3688e0;
  --color-fading-night-600: #2f73bd;
  --color-fading-night-700: #255c98;
  --color-fading-night-800: #164471;
  --color-fading-night-900: #0e2f50;
  --color-fading-night-950: #021b35;
}

SCSS

$fading-night: #2d76c4;
$fading-night-rgb: 45, 118, 196;
$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);
}