Causes a flash of unstyled content when used with Gatsby and styled components

[fwextensions]

I have a simple Gatsby site that uses styled components and MDX: https://github.com/fwextensions/gatsby-test

I noticed that a React component that used SC to style some elements would flash with the wrong font size when the page initially loaded in the built site (running it locally with the dev version worked okay). Something in this bug made me think to disable gatsby-plugin-prettier-build, and that fixed the unstyled flash.

I haven't tried to debug it, as it's easier right now to live with the ugly, unprettified gatsby output to avoid the flash, but wanted to let you know.