#6974A2

CSS

:root {
  --misty-harbour: #6974a2;
  --misty-harbour-rgb: 105 116 162;
  --misty-harbour-oklch: oklch(0.568 0.072 273.5);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(228 23% 52%);
  border-color: oklch(0.568 0.072 273.5);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #6974a2;
  --color-misty-harbour-50: #eff4ff;
  --color-misty-harbour-100: #e1e7ff;
  --color-misty-harbour-200: #cbd2f4;
  --color-misty-harbour-300: #acb5dd;
  --color-misty-harbour-400: #909cca;
  --color-misty-harbour-500: #7783b7;
  --color-misty-harbour-600: #646f9a;
  --color-misty-harbour-700: #50597c;
  --color-misty-harbour-800: #39415c;
  --color-misty-harbour-900: #272d40;
  --color-misty-harbour-950: #151a29;
}

SCSS

$misty-harbour: #6974a2;
$misty-harbour-rgb: 105, 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);
}