#4877BE

CSS

:root {
  --fading-night: #4877be;
  --fading-night-rgb: 72 119 190;
  --fading-night-oklch: oklch(0.569 0.122 258.4);
}

.element {
  color: var(--fading-night);
  background-color: hsl(216 48% 51%);
  border-color: oklch(0.569 0.122 258.4);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #4877be;
  --color-fading-night-50: #e1f6ff;
  --color-fading-night-100: #d1e9ff;
  --color-fading-night-200: #b7d6ff;
  --color-fading-night-300: #93b8f6;
  --color-fading-night-400: #719fe6;
  --color-fading-night-500: #5186d6;
  --color-fading-night-600: #4571b4;
  --color-fading-night-700: #375b91;
  --color-fading-night-800: #25436c;
  --color-fading-night-900: #182e4c;
  --color-fading-night-950: #091b32;
}

SCSS

$fading-night: #4877be;
$fading-night-rgb: 72, 119, 190;
$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);
}