#677499

CSS

:root {
  --misty-harbour: #677499;
  --misty-harbour-rgb: 103 116 153;
  --misty-harbour-oklch: oklch(0.563 0.06 269.4);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(224 20% 50%);
  border-color: oklch(0.563 0.06 269.4);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #677499;
  --color-misty-harbour-50: #eff5ff;
  --color-misty-harbour-100: #e0e7fd;
  --color-misty-harbour-200: #cbd3ef;
  --color-misty-harbour-300: #acb6d7;
  --color-misty-harbour-400: #909dc3;
  --color-misty-harbour-500: #7685ae;
  --color-misty-harbour-600: #647093;
  --color-misty-harbour-700: #505a76;
  --color-misty-harbour-800: #394257;
  --color-misty-harbour-900: #272d3d;
  --color-misty-harbour-950: #151a27;
}

SCSS

$misty-harbour: #677499;
$misty-harbour-rgb: 103, 116, 153;
$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);
}