#1572E2

CSS

:root {
  --fading-night: #1572e2;
  --fading-night-rgb: 21 114 226;
  --fading-night-oklch: oklch(0.566 0.189 256.9);
}

.element {
  color: var(--fading-night);
  background-color: hsl(213 83% 48%);
  border-color: oklch(0.566 0.189 256.9);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #1572e2;
  --color-fading-night-50: #d5f7ff;
  --color-fading-night-100: #c2eaff;
  --color-fading-night-200: #a3d6ff;
  --color-fading-night-300: #7ab8ff;
  --color-fading-night-400: #4d9dff;
  --color-fading-night-500: #1881ff;
  --color-fading-night-600: #186ed7;
  --color-fading-night-700: #1458ad;
  --color-fading-night-800: #024181;
  --color-fading-night-900: #032d5b;
  --color-fading-night-950: #00193e;
}

SCSS

$fading-night: #1572e2;
$fading-night-rgb: 21, 114, 226;
$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);
}