Help for making fake forum threads

So I want to write a fanfic that involves, among other things, a lot of forum threads.
It's basically a kintsugi au of a show i like.

problem is, i don't know how to make fake-forum formatting and google is being super super unhelpful.

any advice?

Specifically in like, ao3 formatting. which is super hard anyway.

 

I dunno if you can reverse-engineer AO3 formatting, but this original fic on AO3 does forum posts convincingly: http://archiveofourown.org/works/3659997/chapters/8143479

 

Gah there is no real way to reverse engineer formatting.
But I really, really want to do the thing.

I guess I can just imitate it with position on page of things

 

ask the person who wrote the thing blue linked

 

Oh yeah! He's nostalgebraist on tumblr, and very friendly

 

Viewing the page source seems to show how the formatting was done

ETA
(Specifically, looks like it's being done with HTML tables, googling that can get you tutorials on how to use them)

 

Awesome thank

 

If you have a hard time figuring out how it works, I am certain nostalgebraist would be willing to help. I've known him for a few years, he's a cool dude.