#4476C7

CSS

:root {
  --fading-night: #4476c7;
  --fading-night-rgb: 68 118 199;
  --fading-night-oklch: oklch(0.571 0.137 259.6);
}

.element {
  color: var(--fading-night);
  background-color: hsl(217 54% 52%);
  border-color: oklch(0.571 0.137 259.6);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #4476c7;
  --color-fading-night-50: #e0f6ff;
  --color-fading-night-100: #cfe9ff;
  --color-fading-night-200: #b4d5ff;
  --color-fading-night-300: #90b8fe;
  --color-fading-night-400: #6d9eef;
  --color-fading-night-500: #4c84df;
  --color-fading-night-600: #4170bc;
  --color-fading-night-700: #345a97;
  --color-fading-night-800: #224271;
  --color-fading-night-900: #162e4f;
  --color-fading-night-950: #071a35;
}

SCSS

$fading-night: #4476c7;
$fading-night-rgb: 68, 118, 199;
$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);
}