#33A5D5

CSS

:root {
  --mystic-blue: #33a5d5;
  --mystic-blue-rgb: 51 165 213;
  --mystic-blue-oklch: oklch(0.68 0.121 230.9);
}

.element {
  color: var(--mystic-blue);
  background-color: hsl(198 66% 52%);
  border-color: oklch(0.68 0.121 230.9);
}

Tailwind CSS v4

@theme {
  --color-mystic-blue: #33a5d5;
  --color-mystic-blue-50: #d4fcff;
  --color-mystic-blue-100: #c1f0ff;
  --color-mystic-blue-200: #a0deff;
  --color-mystic-blue-300: #74c2eb;
  --color-mystic-blue-400: #44abd9;
  --color-mystic-blue-500: #0093c7;
  --color-mystic-blue-600: #007ca8;
  --color-mystic-blue-700: #006487;
  --color-mystic-blue-800: #004a63;
  --color-mystic-blue-900: #003346;
  --color-mystic-blue-950: #001e2d;
}

SCSS

$mystic-blue: #33a5d5;
$mystic-blue-rgb: 51, 165, 213;
$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);
}