#64769F

CSS

:root {
  --misty-harbour: #64769f;
  --misty-harbour-rgb: 100 118 159;
  --misty-harbour-oklch: oklch(0.568 0.067 266);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(222 24% 51%);
  border-color: oklch(0.568 0.067 266);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #64769f;
  --color-misty-harbour-50: #edf5ff;
  --color-misty-harbour-100: #dee8ff;
  --color-misty-harbour-200: #c8d4f2;
  --color-misty-harbour-300: #a8b7db;
  --color-misty-harbour-400: #8c9ec7;
  --color-misty-harbour-500: #7185b3;
  --color-misty-harbour-600: #607198;
  --color-misty-harbour-700: #4d5a7a;
  --color-misty-harbour-800: #36425a;
  --color-misty-harbour-900: #252e3f;
  --color-misty-harbour-950: #141a28;
}

SCSS

$misty-harbour: #64769f;
$misty-harbour-rgb: 100, 118, 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);
}