#2B75CE

CSS

:root {
  --fading-night: #2b75ce;
  --fading-night-rgb: 43 117 206;
  --fading-night-oklch: oklch(0.564 0.155 255.3);
}

.element {
  color: var(--fading-night);
  background-color: hsl(213 65% 49%);
  border-color: oklch(0.564 0.155 255.3);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #2b75ce;
  --color-fading-night-50: #daf8ff;
  --color-fading-night-100: #c8eaff;
  --color-fading-night-200: #aad7ff;
  --color-fading-night-300: #84b9ff;
  --color-fading-night-400: #5ba0f8;
  --color-fading-night-500: #3286ea;
  --color-fading-night-600: #2c71c5;
  --color-fading-night-700: #235b9f;
  --color-fading-night-800: #134376;
  --color-fading-night-900: #0c2e53;
  --color-fading-night-950: #011a38;
}

SCSS

$fading-night: #2b75ce;
$fading-night-rgb: 43, 117, 206;
$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);
}