No text wrapping in the HTML output box

[eliph]

Describe the bug
In the HTML output box, every paragraph of text is being displayed as a single line, no matter how long it is.

To reproduce
Steps to reproduce the behaviour:

1. Go to https://textile-lang.com/doc/acronyms-abbreviations
2. See error

Expected behaviour
Text wrapping, just like in the browser output box, would improve readability of the HTML output.