#4BA5CB

CSS

:root {
  --mystic-blue: #4ba5cb;
  --mystic-blue-rgb: 75 165 203;
  --mystic-blue-oklch: oklch(0.683 0.102 228.7);
}

.element {
  color: var(--mystic-blue);
  background-color: hsl(198 55% 55%);
  border-color: oklch(0.683 0.102 228.7);
}

Tailwind CSS v4

@theme {
  --color-mystic-blue: #4ba5cb;
  --color-mystic-blue-50: #d9fbff;
  --color-mystic-blue-100: #c6efff;
  --color-mystic-blue-200: #a8ddf8;
  --color-mystic-blue-300: #80c1e2;
  --color-mystic-blue-400: #56aace;
  --color-mystic-blue-500: #2492bb;
  --color-mystic-blue-600: #227c9e;
  --color-mystic-blue-700: #1b637f;
  --color-mystic-blue-800: #0f495d;
  --color-mystic-blue-900: #0a3341;
  --color-mystic-blue-950: #001e2a;
}

SCSS

$mystic-blue: #4ba5cb;
$mystic-blue-rgb: 75, 165, 203;
$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);
}