#0A73DD

CSS

:root {
  --fading-night: #0a73dd;
  --fading-night-rgb: 10 115 221;
  --fading-night-oklch: oklch(0.564 0.183 255.2);
}

.element {
  color: var(--fading-night);
  background-color: hsl(210 91% 45%);
  border-color: oklch(0.564 0.183 255.2);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #0a73dd;
  --color-fading-night-50: #d4f8ff;
  --color-fading-night-100: #c1ebff;
  --color-fading-night-200: #a2d7ff;
  --color-fading-night-300: #79b9ff;
  --color-fading-night-400: #4a9fff;
  --color-fading-night-500: #0d83fb;
  --color-fading-night-600: #1270d3;
  --color-fading-night-700: #0f59aa;
  --color-fading-night-800: #00427f;
  --color-fading-night-900: #012e5a;
  --color-fading-night-950: #001a3d;
}

SCSS

$fading-night: #0a73dd;
$fading-night-rgb: 10, 115, 221;
$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);
}