#2B739A

CSS

:root {
  --harbour-blue: #2b739a;
  --harbour-blue-rgb: 43 115 154;
  --harbour-blue-oklch: oklch(0.528 0.093 236.3);
}

.element {
  color: var(--harbour-blue);
  background-color: hsl(201 56% 39%);
  border-color: oklch(0.528 0.093 236.3);
}

Tailwind CSS v4

@theme {
  --color-harbour-blue: #2b739a;
  --color-harbour-blue-50: #defaff;
  --color-harbour-blue-100: #ccedff;
  --color-harbour-blue-200: #b0dbf8;
  --color-harbour-blue-300: #8abfe2;
  --color-harbour-blue-400: #65a7ce;
  --color-harbour-blue-500: #3f8fbc;
  --color-harbour-blue-600: #37799e;
  --color-harbour-blue-700: #2c617f;
  --color-harbour-blue-800: #1d475e;
  --color-harbour-blue-900: #133242;
  --color-harbour-blue-950: #041d2a;
}

SCSS

$harbour-blue: #2b739a;
$harbour-blue-rgb: 43, 115, 154;
$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);
}