Make shell text scrollable horizontally

[TisVictress]

I noticed that shell text is not scrollable horizontally. Instead, the shell text block is expanded to fit all the text and takes up lots of vertical space. This is super noticeable on mobile:

I'm not sure how to go about fixing this because editing CSS in the blog is notoriously tedious.

[OonihiloO]

Hi @TisVictress: thanks for the review and the merge.
I forgot to link the issue to your project when I linked my PR should have use (closes packet-buildpack/blog#61 in my commit message).
You might have to manually close this issue.
Sorry for the error and thanks again for all your great work!