#4574C2

CSS

:root {
  --fading-night: #4574c2;
  --fading-night-rgb: 69 116 194;
  --fading-night-oklch: oklch(0.564 0.132 260);
}

.element {
  color: var(--fading-night);
  background-color: hsl(217 51% 52%);
  border-color: oklch(0.564 0.132 260);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #4574c2;
  --color-fading-night-50: #e1f6ff;
  --color-fading-night-100: #d0e9ff;
  --color-fading-night-200: #b6d5ff;
  --color-fading-night-300: #92b8fb;
  --color-fading-night-400: #6f9eec;
  --color-fading-night-500: #5084dc;
  --color-fading-night-600: #4470ba;
  --color-fading-night-700: #365a95;
  --color-fading-night-800: #24426f;
  --color-fading-night-900: #182e4e;
  --color-fading-night-950: #091a34;
}

SCSS

$fading-night: #4574c2;
$fading-night-rgb: 69, 116, 194;
$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);
}