#41728C

CSS

:root {
  --harbour-blue: #41728c;
  --harbour-blue-rgb: 65 114 140;
  --harbour-blue-oklch: oklch(0.528 0.067 233.2);
}

.element {
  color: var(--harbour-blue);
  background-color: hsl(201 37% 40%);
  border-color: oklch(0.528 0.067 233.2);
}

Tailwind CSS v4

@theme {
  --color-harbour-blue: #41728c;
  --color-harbour-blue-50: #e4f9ff;
  --color-harbour-blue-100: #d3ecfc;
  --color-harbour-blue-200: #badaed;
  --color-harbour-blue-300: #97bed5;
  --color-harbour-blue-400: #76a6c0;
  --color-harbour-blue-500: #578eac;
  --color-harbour-blue-600: #4a7891;
  --color-harbour-blue-700: #3b6074;
  --color-harbour-blue-800: #294756;
  --color-harbour-blue-900: #1c313c;
  --color-harbour-blue-950: #0c1d25;
}

SCSS

$harbour-blue: #41728c;
$harbour-blue-rgb: 65, 114, 140;
$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);
}