#6D7691

CSS

:root {
  --misty-harbour: #6d7691;
  --misty-harbour-rgb: 109 118 145;
  --misty-harbour-oklch: oklch(0.568 0.043 270.5);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(225 14% 50%);
  border-color: oklch(0.568 0.043 270.5);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #6d7691;
  --color-misty-harbour-50: #f1f5ff;
  --color-misty-harbour-100: #e3e7f7;
  --color-misty-harbour-200: #ced4e7;
  --color-misty-harbour-300: #b0b7ce;
  --color-misty-harbour-400: #949eb9;
  --color-misty-harbour-500: #7b85a4;
  --color-misty-harbour-600: #68718a;
  --color-misty-harbour-700: #535a6f;
  --color-misty-harbour-800: #3c4252;
  --color-misty-harbour-900: #292e39;
  --color-misty-harbour-950: #171a23;
}

SCSS

$misty-harbour: #6d7691;
$misty-harbour-rgb: 109, 118, 145;
$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);
}