#53A4C8

CSS

:root {
  --mystic-blue: #53a4c8;
  --mystic-blue-rgb: 83 164 200;
  --mystic-blue-oklch: oklch(0.682 0.095 229.4);
}

.element {
  color: var(--mystic-blue);
  background-color: hsl(198 52% 55%);
  border-color: oklch(0.682 0.095 229.4);
}

Tailwind CSS v4

@theme {
  --color-mystic-blue: #53a4c8;
  --color-mystic-blue-50: #dbfbff;
  --color-mystic-blue-100: #c9eeff;
  --color-mystic-blue-200: #acdcf6;
  --color-mystic-blue-300: #84c1e0;
  --color-mystic-blue-400: #5ea9cc;
  --color-mystic-blue-500: #3292b8;
  --color-mystic-blue-600: #2c7b9c;
  --color-mystic-blue-700: #23637d;
  --color-mystic-blue-800: #16495c;
  --color-mystic-blue-900: #0e3240;
  --color-mystic-blue-950: #021e29;
}

SCSS

$mystic-blue: #53a4c8;
$mystic-blue-rgb: 83, 164, 200;
$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);
}