I really want a nice wysiwyg markdown editor. Not the two column layout. I want syntax highlighting, but it should not only do colors but also semantics. Headings should be actually bigger and italics slanted.

I tried and failed to make this idea a reality. I got to partial solution using regular expressions. But it is far from functional and reliable but it is only like 200 lines!

You can check it out here: https://dl.dropboxusercontent.com/u/52646091/syntax/selectio...