#6A729D

CSS

:root {
  --misty-harbour: #6a729d;
  --misty-harbour-rgb: 106 114 157;
  --misty-harbour-oklch: oklch(0.562 0.067 275.9);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(231 21% 52%);
  border-color: oklch(0.562 0.067 275.9);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #6a729d;
  --color-misty-harbour-50: #f0f4ff;
  --color-misty-harbour-100: #e2e6ff;
  --color-misty-harbour-200: #cdd2f2;
  --color-misty-harbour-300: #afb5da;
  --color-misty-harbour-400: #939cc7;
  --color-misty-harbour-500: #7a83b3;
  --color-misty-harbour-600: #676f97;
  --color-misty-harbour-700: #525879;
  --color-misty-harbour-800: #3b415a;
  --color-misty-harbour-900: #282d3f;
  --color-misty-harbour-950: #161a28;
}

SCSS

$misty-harbour: #6a729d;
$misty-harbour-rgb: 106, 114, 157;
$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);
}