Is this possibly the same as this issue?
Can you post an image of the html_document output in a separate message? (edited to add: I mean in this thread, not in a new thread, in case that wasn't clear)
(as in so many things on the internet, the reason for limits on new users who are necessarily of as-yet-unknown trustworthiness is that these limits make the site less attractive to abuse by spambots, sock puppets, and trolls 
)