#3A7292

CSS

:root {
  --harbour-blue: #3a7292;
  --harbour-blue-rgb: 58 114 146;
  --harbour-blue-oklch: oklch(0.528 0.078 235.9);
}

.element {
  color: var(--harbour-blue);
  background-color: hsl(202 43% 40%);
  border-color: oklch(0.528 0.078 235.9);
}

Tailwind CSS v4

@theme {
  --color-harbour-blue: #3a7292;
  --color-harbour-blue-50: #e1f9ff;
  --color-harbour-blue-100: #d1ecff;
  --color-harbour-blue-200: #b6daf2;
  --color-harbour-blue-300: #92bedb;
  --color-harbour-blue-400: #71a6c6;
  --color-harbour-blue-500: #4f8eb3;
  --color-harbour-blue-600: #447897;
  --color-harbour-blue-700: #366079;
  --color-harbour-blue-800: #254759;
  --color-harbour-blue-900: #19313e;
  --color-harbour-blue-950: #091d28;
}

SCSS

$harbour-blue: #3a7292;
$harbour-blue-rgb: 58, 114, 146;
$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);
}