#4075C0

CSS

:root {
  --fading-night: #4075c0;
  --fading-night-rgb: 64 117 192;
  --fading-night-oklch: oklch(0.562 0.13 257.4);
}

.element {
  color: var(--fading-night);
  background-color: hsl(215 50% 50%);
  border-color: oklch(0.562 0.13 257.4);
}

Tailwind CSS v4

@theme {
  --color-fading-night: #4075c0;
  --color-fading-night-50: #dff7ff;
  --color-fading-night-100: #cfeaff;
  --color-fading-night-200: #b3d6ff;
  --color-fading-night-300: #8fb9fa;
  --color-fading-night-400: #6ca0ea;
  --color-fading-night-500: #4a86db;
  --color-fading-night-600: #4072b8;
  --color-fading-night-700: #335b94;
  --color-fading-night-800: #21436e;
  --color-fading-night-900: #162e4e;
  --color-fading-night-950: #071b33;
}

SCSS

$fading-night: #4075c0;
$fading-night-rgb: 64, 117, 192;
$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);
}