#0D77D8

CSS

:root {
  --fading-night: #0d77d8;
  --fading-night-rgb: 13 119 216;
  --fading-night-oklch: oklch(0.569 0.171 253.2);
}

.element {
  color: var(--fading-night);
  background-color: hsl(209 89% 45%);
  border-color: oklch(0.569 0.171 253.2);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #0d77d8;
  --color-fading-night-50: #d5f8ff;
  --color-fading-night-100: #c2ebff;
  --color-fading-night-200: #a2d8ff;
  --color-fading-night-300: #79baff;
  --color-fading-night-400: #4ba1ff;
  --color-fading-night-500: #0b86f3;
  --color-fading-night-600: #1172cd;
  --color-fading-night-700: #0f5ba5;
  --color-fading-night-800: #00437b;
  --color-fading-night-900: #022f57;
  --color-fading-night-950: #001b3b;
}

SCSS

$fading-night: #0d77d8;
$fading-night-rgb: 13, 119, 216;
$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);
}