#6875A3

CSS

:root {
  --misty-harbour: #6875a3;
  --misty-harbour-rgb: 104 117 163;
  --misty-harbour-oklch: oklch(0.57 0.073 271.8);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(227 24% 52%);
  border-color: oklch(0.57 0.073 271.8);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #6875a3;
  --color-misty-harbour-50: #eef4ff;
  --color-misty-harbour-100: #e0e7ff;
  --color-misty-harbour-200: #cad3f4;
  --color-misty-harbour-300: #abb5de;
  --color-misty-harbour-400: #8f9cca;
  --color-misty-harbour-500: #7583b7;
  --color-misty-harbour-600: #636f9b;
  --color-misty-harbour-700: #4f597c;
  --color-misty-harbour-800: #38415c;
  --color-misty-harbour-900: #262d40;
  --color-misty-harbour-950: #151a29;
}

SCSS

$misty-harbour: #6875a3;
$misty-harbour-rgb: 104, 117, 163;
$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);
}