#6974A4

CSS

:root {
  --misty-harbour: #6974a4;
  --misty-harbour-rgb: 105 116 164;
  --misty-harbour-oklch: oklch(0.569 0.075 273.9);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(229 24% 53%);
  border-color: oklch(0.569 0.075 273.9);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #6974a4;
  --color-misty-harbour-50: #eff4ff;
  --color-misty-harbour-100: #e0e6ff;
  --color-misty-harbour-200: #cbd2f5;
  --color-misty-harbour-300: #acb5df;
  --color-misty-harbour-400: #909ccc;
  --color-misty-harbour-500: #7683b9;
  --color-misty-harbour-600: #646f9c;
  --color-misty-harbour-700: #50587d;
  --color-misty-harbour-800: #39415d;
  --color-misty-harbour-900: #272d41;
  --color-misty-harbour-950: #151a2a;
}

SCSS

$misty-harbour: #6974a4;
$misty-harbour-rgb: 105, 116, 164;
$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);
}