Hi all! Thanks for using Ghost and taking an interest in our Gatsby starter 
The Gatsby Starter we’ve made is designed to be exactly that, a starter for people wanting to build their own Gatsby site with Ghost as a headless CMS. We didn’t want it to match Casper exactly as many people will clone this Starter and begin to style it to their own needs.
That doesn’t mean to say you can’t copy the design of Casper into a Gatsby theme of your own! Looks like there’s a couple of people that have already done just that: