#2E74DA

CSS

:root {
  --fading-night: #2e74da;
  --fading-night-rgb: 46 116 218;
  --fading-night-oklch: oklch(0.57 0.171 258.3);
}

.element {
  color: var(--fading-night);
  background-color: hsl(216 70% 52%);
  border-color: oklch(0.57 0.171 258.3);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #2e74da;
  --color-fading-night-50: #d9f7ff;
  --color-fading-night-100: #c7e9ff;
  --color-fading-night-200: #aad5ff;
  --color-fading-night-300: #83b7ff;
  --color-fading-night-400: #5b9eff;
  --color-fading-night-500: #3382f5;
  --color-fading-night-600: #2d6ece;
  --color-fading-night-700: #2458a6;
  --color-fading-night-800: #13417c;
  --color-fading-night-900: #0c2d58;
  --color-fading-night-950: #01193b;
}

SCSS

$fading-night: #2e74da;
$fading-night-rgb: 46, 116, 218;
$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);
}