#2A73D4

CSS

:root {
  --fading-night: #2a73d4;
  --fading-night-rgb: 42 115 212;
  --fading-night-oklch: oklch(0.563 0.166 257.1);
}

.element {
  color: var(--fading-night);
  background-color: hsl(214 67% 50%);
  border-color: oklch(0.563 0.166 257.1);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #2a73d4;
  --color-fading-night-50: #d9f7ff;
  --color-fading-night-100: #c7eaff;
  --color-fading-night-200: #aad6ff;
  --color-fading-night-300: #83b8ff;
  --color-fading-night-400: #5a9ffe;
  --color-fading-night-500: #3184f1;
  --color-fading-night-600: #2b70cb;
  --color-fading-night-700: #2259a3;
  --color-fading-night-800: #12427a;
  --color-fading-night-900: #0b2e56;
  --color-fading-night-950: #011a3a;
}

SCSS

$fading-night: #2a73d4;
$fading-night-rgb: 42, 115, 212;
$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);
}