My point is, what you're trying to accomplish with markdown is just as easy to accomplish with good old-fashioned HTML.
If you want nice CSS, define it and tell your users how to use it.
Rather than running everything through markdown, run it through an XHTML whitelist.
You don't write an entire page in markdown, generally - you just write a fragment. So, let me write an HTML fragment, and you can wrap it with the headers you need to.
You cannot expect users to know HTML and CSS to comment on your website.
Hacker News could probably expect a large majority of their users to be able to handle it. Maybe with complaints, but handle it.
I had a personal Wiki which was based off of some open source Wiki. The first thing I did was removed Markdown, because it was completely pointless for me. This was 14 years ago. All I wanted was a web interface to edit HTML and view it later. For the most part, I just had lists and links, and sometimes notes and status reports.
Mainly, I could go to localhost/psychometry in my browser bar, and get immediately presented with "This page doesn't exist, type in the textbox below to write the HTML for the page". It was super handy.
but it's not entirely accurate to say it was "invented".
let me be more clear: markdown was _not_ "invented".
gruber was blogging with movable type, which was using the _textile_ light-markup system created by dean allen.
so he didn't even come up with the _idea_ himself!
of course, neither did allen. light-markup systems were _the_zeitgeist_ around the turn of the century:
* restructured-text was adopted for python documentation.
(.rst -wikipedia.org/wiki/restructuredtext -- david goodger)
* asciidoc had a big list of org-users. (still does.)
(asciidoc -- wikipedia.org/wiki/asciidoc -- stuart rackham)
* and there were other early entrants that are still alive.
(txt2tags -- wikipedia.org/wiki/txt2tags -- txt2tags team)
and dean allen's textile had a fairly solid reach by 2004:
* textile -- wikipedia.org/wiki/textpattern -- dean allen
* texy -- code.google.com/p/texy-- david grudl
* redcloth -- rubygems.org/gems/RedCloth/versions -- garber
* textpattern -- textpattern.com -- dean allen
but the first that i'd call "light markup" was "setext":
* 1992 -- http://en.wikipedia.org/wiki/setext -- ian feldman
"setext" was short for "structured e-text", and yes, that's why "restructured-text" put the "re" in front of its name, because they were "redoing" the structured-e-text of setext.
but even ian feldman would tell you (if you could find him) that he was merely leveraging the well-known conventions of the fledging internet at the time, such as usenet listserves.
"light-markup" is something that _the_masses_ "invented".
-bowerbird