#2D75CC

CSS

:root {
  --fading-night: #2d75cc;
  --fading-night-rgb: 45 117 204;
  --fading-night-oklch: oklch(0.563 0.152 255.3);
}

.element {
  color: var(--fading-night);
  background-color: hsl(213 64% 49%);
  border-color: oklch(0.563 0.152 255.3);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #2d75cc;
  --color-fading-night-50: #daf8ff;
  --color-fading-night-100: #c8eaff;
  --color-fading-night-200: #abd7ff;
  --color-fading-night-300: #85b9ff;
  --color-fading-night-400: #5da0f6;
  --color-fading-night-500: #3586e8;
  --color-fading-night-600: #2e71c4;
  --color-fading-night-700: #255b9d;
  --color-fading-night-800: #144375;
  --color-fading-night-900: #0d2e53;
  --color-fading-night-950: #021b37;
}

SCSS

$fading-night: #2d75cc;
$fading-night-rgb: 45, 117, 204;
$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);
}