If you are using a Retina screen, it is indeed possible that our creator tool seems slightly blurry.

How do I know if I am using a Retina screen?

You can follow these steps to find out:

1. Open the Apple menu on the top left of your screen.
2. Choose "About this Mac".

You’ll get a screen that will tell you which MacBook you have, including whether it has a Retina display.