#397291

CSS

:root {
  --harbour-blue: #397291;
  --harbour-blue-rgb: 57 114 145;
  --harbour-blue-oklch: oklch(0.527 0.077 234.6);
}

.element {
  color: var(--harbour-blue);
  background-color: hsl(201 44% 40%);
  border-color: oklch(0.527 0.077 234.6);
}

Tailwind CSS v4

@theme {
  --color-harbour-blue: #397291;
  --color-harbour-blue-50: #e1f9ff;
  --color-harbour-blue-100: #d1edff;
  --color-harbour-blue-200: #b6daf2;
  --color-harbour-blue-300: #92beda;
  --color-harbour-blue-400: #70a6c6;
  --color-harbour-blue-500: #4e8eb2;
  --color-harbour-blue-600: #437996;
  --color-harbour-blue-700: #356079;
  --color-harbour-blue-800: #254759;
  --color-harbour-blue-900: #18313e;
  --color-harbour-blue-950: #091d27;
}

SCSS

$harbour-blue: #397291;
$harbour-blue-rgb: 57, 114, 145;
$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);
}