#377390

CSS

:root {
  --harbour-blue: #377390;
  --harbour-blue-rgb: 55 115 144;
  --harbour-blue-oklch: oklch(0.528 0.077 231.7);
}

.element {
  color: var(--harbour-blue);
  background-color: hsl(200 45% 39%);
  border-color: oklch(0.528 0.077 231.7);
}

Tailwind CSS v4

@theme {
  --color-harbour-blue: #377390;
  --color-harbour-blue-50: #e1faff;
  --color-harbour-blue-100: #d0edfe;
  --color-harbour-blue-200: #b5dbf1;
  --color-harbour-blue-300: #91bfd9;
  --color-harbour-blue-400: #6ea7c4;
  --color-harbour-blue-500: #4c8fb0;
  --color-harbour-blue-600: #417995;
  --color-harbour-blue-700: #346177;
  --color-harbour-blue-800: #234758;
  --color-harbour-blue-900: #18313d;
  --color-harbour-blue-950: #081d27;
}

SCSS

$harbour-blue: #377390;
$harbour-blue-rgb: 55, 115, 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);
}