#41718F

CSS

:root {
  --harbour-blue: #41718f;
  --harbour-blue-rgb: 65 113 143;
  --harbour-blue-oklch: oklch(0.527 0.071 237.6);
}

.element {
  color: var(--harbour-blue);
  background-color: hsl(203 38% 41%);
  border-color: oklch(0.527 0.071 237.6);
}

Tailwind CSS v4

@theme {
  --color-harbour-blue: #41718f;
  --color-harbour-blue-50: #e4f9ff;
  --color-harbour-blue-100: #d3ecfe;
  --color-harbour-blue-200: #bad9f0;
  --color-harbour-blue-300: #97bdd8;
  --color-harbour-blue-400: #76a5c3;
  --color-harbour-blue-500: #578db0;
  --color-harbour-blue-600: #4a7794;
  --color-harbour-blue-700: #3b6077;
  --color-harbour-blue-800: #294658;
  --color-harbour-blue-900: #1c313d;
  --color-harbour-blue-950: #0c1d27;
}

SCSS

$harbour-blue: #41718f;
$harbour-blue-rgb: 65, 113, 143;
$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);
}