#1D72DF

CSS

:root {
  --fading-night: #1d72df;
  --fading-night-rgb: 29 114 223;
  --fading-night-oklch: oklch(0.566 0.184 257.3);
}

.element {
  color: var(--fading-night);
  background-color: hsl(214 77% 49%);
  border-color: oklch(0.566 0.184 257.3);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #1d72df;
  --color-fading-night-50: #d6f7ff;
  --color-fading-night-100: #c4eaff;
  --color-fading-night-200: #a5d6ff;
  --color-fading-night-300: #7db8ff;
  --color-fading-night-400: #519eff;
  --color-fading-night-500: #2282fc;
  --color-fading-night-600: #1f6ed5;
  --color-fading-night-700: #1958ab;
  --color-fading-night-800: #074180;
  --color-fading-night-900: #052d5a;
  --color-fading-night-950: #00193d;
}

SCSS

$fading-night: #1d72df;
$fading-night-rgb: 29, 114, 223;
$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);
}