docs(css): Fix word breaks issue in <pre>

[gsklee]

Closes #6586

[mary-poppins]

Thanks for the PR! Please check the items below to help us merge this faster. See the contributing docs for more information.

• Uses the issue template (#6588)

If you need to make changes to your pull request, you can update the commit with git commit --amend.
Then, update the pull request with git push -f.

Thanks again for your help!

[btford]

Landed as ee07b50. Thanks @gsklee!