#67739F

CSS

:root {
  --misty-harbour: #67739f;
  --misty-harbour-rgb: 103 115 159;
  --misty-harbour-oklch: oklch(0.563 0.07 272.3);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(227 23% 51%);
  border-color: oklch(0.563 0.07 272.3);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #67739f;
  --color-misty-harbour-50: #eff4ff;
  --color-misty-harbour-100: #e0e7ff;
  --color-misty-harbour-200: #cbd3f3;
  --color-misty-harbour-300: #acb5dc;
  --color-misty-harbour-400: #909cc8;
  --color-misty-harbour-500: #7683b5;
  --color-misty-harbour-600: #646f99;
  --color-misty-harbour-700: #50597b;
  --color-misty-harbour-800: #39415b;
  --color-misty-harbour-900: #272d40;
  --color-misty-harbour-950: #151a29;
}

SCSS

$misty-harbour: #67739f;
$misty-harbour-rgb: 103, 115, 159;
$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);
}