Fly-by-Night

CSS

:root {
  --fly-by-night: #1c1e4d;
  --fly-by-night-rgb: 28 30 77;
  --fly-by-night-oklch: oklch(0.264 0.085 277);
}

.element {
  color: var(--fly-by-night);
  background-color: hsl(238 47% 21%);
  border-color: oklch(0.264 0.085 277);
}

Tailwind CSS v4

@theme {
  --color-fly-by-night: #1c1e4d;
  --color-fly-by-night-50: #eff3ff;
  --color-fly-by-night-100: #e1e6ff;
  --color-fly-by-night-200: #ccd1f9;
  --color-fly-by-night-300: #adb4e3;
  --color-fly-by-night-400: #919ad1;
  --color-fly-by-night-500: #7881be;
  --color-fly-by-night-600: #656da1;
  --color-fly-by-night-700: #515781;
  --color-fly-by-night-800: #3a4060;
  --color-fly-by-night-900: #272c43;
  --color-fly-by-night-950: #16192b;
}

SCSS

$fly-by-night: #1c1e4d;
$fly-by-night-rgb: 28, 30, 77;
$fly-by-night-light: mix(#fff, $fly-by-night, 20%);
$fly-by-night-dark: mix(#000, $fly-by-night, 20%);

.element {
  color: $fly-by-night;
  box-shadow: 0 0 0 2px rgba($fly-by-night, 0.35);
}