#427190

CSS

:root {
  --harbour-blue: #427190;
  --harbour-blue-rgb: 66 113 144;
  --harbour-blue-oklch: oklch(0.528 0.071 239);
}

.element {
  color: var(--harbour-blue);
  background-color: hsl(204 37% 41%);
  border-color: oklch(0.528 0.071 239);
}

Tailwind CSS v4

@theme {
  --color-harbour-blue: #427190;
  --color-harbour-blue-50: #e4f8ff;
  --color-harbour-blue-100: #d4ecfe;
  --color-harbour-blue-200: #bad9f0;
  --color-harbour-blue-300: #97bdd9;
  --color-harbour-blue-400: #77a5c4;
  --color-harbour-blue-500: #588db0;
  --color-harbour-blue-600: #4b7795;
  --color-harbour-blue-700: #3c5f77;
  --color-harbour-blue-800: #294658;
  --color-harbour-blue-900: #1c313d;
  --color-harbour-blue-950: #0c1d27;
}

SCSS

$harbour-blue: #427190;
$harbour-blue-rgb: 66, 113, 144;
$harbour-blue-light: mix(#fff, $harbour-blue, 20%);
$harbour-blue-dark: mix(#000, $harbour-blue, 20%);

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