#53A4C9

CSS

:root {
  --mystic-blue: #53a4c9;
  --mystic-blue-rgb: 83 164 201;
  --mystic-blue-oklch: oklch(0.682 0.096 230.1);
}

.element {
  color: var(--mystic-blue);
  background-color: hsl(199 52% 56%);
  border-color: oklch(0.682 0.096 230.1);
}

Tailwind CSS v4

@theme {
  --color-mystic-blue: #53a4c9;
  --color-mystic-blue-50: #dbfbff;
  --color-mystic-blue-100: #c9eeff;
  --color-mystic-blue-200: #acdcf7;
  --color-mystic-blue-300: #84c1e0;
  --color-mystic-blue-400: #5da9cc;
  --color-mystic-blue-500: #3291b9;
  --color-mystic-blue-600: #2c7b9d;
  --color-mystic-blue-700: #23627e;
  --color-mystic-blue-800: #16495c;
  --color-mystic-blue-900: #0e3241;
  --color-mystic-blue-950: #021e29;
}

SCSS

$mystic-blue: #53a4c9;
$mystic-blue-rgb: 83, 164, 201;
$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);
}