#5F74A2

CSS

:root {
  --misty-harbour: #5f74a2;
  --misty-harbour-rgb: 95 116 162;
  --misty-harbour-oklch: oklch(0.561 0.076 265.2);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(221 26% 50%);
  border-color: oklch(0.561 0.076 265.2);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #5f74a2;
  --color-misty-harbour-50: #ebf5ff;
  --color-misty-harbour-100: #dce8ff;
  --color-misty-harbour-200: #c6d4f6;
  --color-misty-harbour-300: #a6b7df;
  --color-misty-harbour-400: #899ecc;
  --color-misty-harbour-500: #6e85b9;
  --color-misty-harbour-600: #5d719c;
  --color-misty-harbour-700: #4a5a7d;
  --color-misty-harbour-800: #34425d;
  --color-misty-harbour-900: #242e41;
  --color-misty-harbour-950: #131a2a;
}

SCSS

$misty-harbour: #5f74a2;
$misty-harbour-rgb: 95, 116, 162;
$misty-harbour-light: mix(#fff, $misty-harbour, 20%);
$misty-harbour-dark: mix(#000, $misty-harbour, 20%);

.element {
  color: $misty-harbour;
  box-shadow: 0 0 0 2px rgba($misty-harbour, 0.35);
}