#457190

CSS

:root {
  --harbour-blue: #457190;
  --harbour-blue-rgb: 69 113 144;
  --harbour-blue-oklch: oklch(0.53 0.069 240.5);
}

.element {
  color: var(--harbour-blue);
  background-color: hsl(205 35% 42%);
  border-color: oklch(0.53 0.069 240.5);
}

Tailwind CSS v4

@theme {
  --color-harbour-blue: #457190;
  --color-harbour-blue-50: #e5f8ff;
  --color-harbour-blue-100: #d5ebfe;
  --color-harbour-blue-200: #bbd9f0;
  --color-harbour-blue-300: #99bcd8;
  --color-harbour-blue-400: #79a4c4;
  --color-harbour-blue-500: #5a8cb0;
  --color-harbour-blue-600: #4d7794;
  --color-harbour-blue-700: #3d5f77;
  --color-harbour-blue-800: #2b4658;
  --color-harbour-blue-900: #1d303d;
  --color-harbour-blue-950: #0d1d27;
}

SCSS

$harbour-blue: #457190;
$harbour-blue-rgb: 69, 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);
}