#607697

CSS

:root {
  --misty-harbour: #607697;
  --misty-harbour-rgb: 96 118 151;
  --misty-harbour-oklch: oklch(0.561 0.058 258.3);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(216 22% 48%);
  border-color: oklch(0.561 0.058 258.3);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #607697;
  --color-misty-harbour-50: #ecf6ff;
  --color-misty-harbour-100: #dde9fc;
  --color-misty-harbour-200: #c6d5ee;
  --color-misty-harbour-300: #a7b8d6;
  --color-misty-harbour-400: #8aa0c1;
  --color-misty-harbour-500: #6f88ad;
  --color-misty-harbour-600: #5e7392;
  --color-misty-harbour-700: #4b5c75;
  --color-misty-harbour-800: #354356;
  --color-misty-harbour-900: #242e3c;
  --color-misty-harbour-950: #131b26;
}

SCSS

$misty-harbour: #607697;
$misty-harbour-rgb: 96, 118, 151;
$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);
}