#54A4CA

CSS

:root {
  --mystic-blue: #54a4ca;
  --mystic-blue-rgb: 84 164 202;
  --mystic-blue-oklch: oklch(0.683 0.096 231.1);
}

.element {
  color: var(--mystic-blue);
  background-color: hsl(199 53% 56%);
  border-color: oklch(0.683 0.096 231.1);
}

Tailwind CSS v4

@theme {
  --color-mystic-blue: #54a4ca;
  --color-mystic-blue-50: #dbfbff;
  --color-mystic-blue-100: #c9eeff;
  --color-mystic-blue-200: #acdcf7;
  --color-mystic-blue-300: #85c0e1;
  --color-mystic-blue-400: #5ea9cd;
  --color-mystic-blue-500: #3391ba;
  --color-mystic-blue-600: #2d7b9d;
  --color-mystic-blue-700: #24627e;
  --color-mystic-blue-800: #16485d;
  --color-mystic-blue-900: #0f3241;
  --color-mystic-blue-950: #021e2a;
}

SCSS

$mystic-blue: #54a4ca;
$mystic-blue-rgb: 84, 164, 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);
}