#6575A7

CSS

:root {
  --misty-harbour: #6575a7;
  --misty-harbour-rgb: 101 117 167;
  --misty-harbour-oklch: oklch(0.57 0.08 270.1);
}

.element {
  color: var(--misty-harbour);
  background-color: hsl(225 27% 53%);
  border-color: oklch(0.57 0.08 270.1);
}

Tailwind CSS v4

@theme {
  --color-misty-harbour: #6575a7;
  --color-misty-harbour-50: #edf4ff;
  --color-misty-harbour-100: #dee7ff;
  --color-misty-harbour-200: #c8d3f7;
  --color-misty-harbour-300: #a9b6e1;
  --color-misty-harbour-400: #8c9dce;
  --color-misty-harbour-500: #7283bc;
  --color-misty-harbour-600: #606f9e;
  --color-misty-harbour-700: #4d597f;
  --color-misty-harbour-800: #36415e;
  --color-misty-harbour-900: #252d42;
  --color-misty-harbour-950: #141a2a;
}

SCSS

$misty-harbour: #6575a7;
$misty-harbour-rgb: 101, 117, 167;
$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);
}