#4CA5CA

CSS

:root {
  --mystic-blue: #4ca5ca;
  --mystic-blue-rgb: 76 165 202;
  --mystic-blue-oklch: oklch(0.683 0.101 228.2);
}

.element {
  color: var(--mystic-blue);
  background-color: hsl(198 54% 55%);
  border-color: oklch(0.683 0.101 228.2);
}

Tailwind CSS v4

@theme {
  --color-mystic-blue: #4ca5ca;
  --color-mystic-blue-50: #d9fbff;
  --color-mystic-blue-100: #c7efff;
  --color-mystic-blue-200: #a8ddf7;
  --color-mystic-blue-300: #80c1e1;
  --color-mystic-blue-400: #57aacd;
  --color-mystic-blue-500: #2692ba;
  --color-mystic-blue-600: #237c9d;
  --color-mystic-blue-700: #1c637e;
  --color-mystic-blue-800: #10495d;
  --color-mystic-blue-900: #0a3341;
  --color-mystic-blue-950: #001e2a;
}

SCSS

$mystic-blue: #4ca5ca;
$mystic-blue-rgb: 76, 165, 202;
$mystic-blue-light: mix(#fff, $mystic-blue, 20%);
$mystic-blue-dark: mix(#000, $mystic-blue, 20%);

.element {
  color: $mystic-blue;
  box-shadow: 0 0 0 2px rgba($mystic-blue, 0.35);
}