Once in a Blue Moon

CSS

:root {
  --once-in-a-blue-moon: #0044bb;
  --once-in-a-blue-moon-rgb: 0 68 187;
  --once-in-a-blue-moon-oklch: oklch(0.437 0.196 261.6);
}

.element {
  color: var(--once-in-a-blue-moon);
  background-color: hsl(218 100% 37%);
  border-color: oklch(0.437 0.196 261.6);
}

Tailwind CSS v4

@theme {
  --color-once-in-a-blue-moon: #0044bb;
  --color-once-in-a-blue-moon-50: #d8f6ff;
  --color-once-in-a-blue-moon-100: #c6e8ff;
  --color-once-in-a-blue-moon-200: #a9d3ff;
  --color-once-in-a-blue-moon-300: #83b4ff;
  --color-once-in-a-blue-moon-400: #5a9aff;
  --color-once-in-a-blue-moon-500: #347cff;
  --color-once-in-a-blue-moon-600: #2d6adc;
  --color-once-in-a-blue-moon-700: #2455b1;
  --color-once-in-a-blue-moon-800: #123e85;
  --color-once-in-a-blue-moon-900: #0b2b5e;
  --color-once-in-a-blue-moon-950: #011840;
}

SCSS

$once-in-a-blue-moon: #0044bb;
$once-in-a-blue-moon-rgb: 0, 68, 187;
$once-in-a-blue-moon-light: mix(#fff, $once-in-a-blue-moon, 20%);
$once-in-a-blue-moon-dark: mix(#000, $once-in-a-blue-moon, 20%);

.element {
  color: $once-in-a-blue-moon;
  box-shadow: 0 0 0 2px rgba($once-in-a-blue-moon, 0.35);
}