#6673A0

CSS

:root {
  --misty-harbour: #6673a0;
  --misty-harbour-rgb: 102 115 160;
  --misty-harbour-oklch: oklch(0.563 0.072 271.6);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(227 23% 51%);
  border-color: oklch(0.563 0.072 271.6);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #6673a0;
  --color-misty-harbour-50: #eef4ff;
  --color-misty-harbour-100: #e0e7ff;
  --color-misty-harbour-200: #cad3f4;
  --color-misty-harbour-300: #abb5dd;
  --color-misty-harbour-400: #8f9cca;
  --color-misty-harbour-500: #7584b6;
  --color-misty-harbour-600: #636f9a;
  --color-misty-harbour-700: #4f597b;
  --color-misty-harbour-800: #38415c;
  --color-misty-harbour-900: #272d40;
  --color-misty-harbour-950: #151a29;
}

SCSS

$misty-harbour: #6673a0;
$misty-harbour-rgb: 102, 115, 160;
$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);
}