Pages with code samples don't shrink properly in Firefox thus making the pages unreadable on mobile

I use Firefox on Android as my main browser and every time I follow a link from Twitter to the React docs, I inevitably can't read them without then copying the link in to Chrome because body has overflow-x: hidden and the .gatsby-highlight code samples don't wrap like they do in other browsers.

An example, broken page is https://reactjs.org/docs/add-react-to-a-website.html

This issue can also be reproduced in desktop Firefox:

Personally, I don't think that code samples should wrap and they should have their own horizontal scroll, but I'll leave it up to you which you think is the best course of action. Regardless, I'd be happy to try and fix it, whichever solution you decide on.

Beginne damit, die Beispielseite in Firefox auf Android oder dem Desktop nachzubilden, und untersuche dann die Styles für body overflow-x und die Codebeispiele in .gatsby-highlight. Als erledigt gilt die Aufgabe, wenn die Dokumentationsseite auf Mobilgeräten lesbar bleibt und Codebeispiele entweder umbrechen oder eigenes horizontales Scrollen ermöglichen.