|It's way more helpful to post an article and share the code than it is to advertise your project on the Lounge. Imagine if everyone posted "hey, check out my new tool" message. I'm going to move this to the free tools forum.
Besides that, I have two comments
1. Well done. I too am writing Yet Another Markdown Processor myself because the current ones are too ambiguous and don't have everything I want. It's a PITA to get all the cases right.
2. I don't, however, understand the motivation for creating yet another syntax that's not compatible with markdown just to add styling. Markdown already includes the ability to include plain HTML with styles and classes. Further, the intent of Markdown is that "a Markdown-formatted document should be publishable as-is, as plain text, without looking like it’s been marked up with tags or formatting instructions". So what you've proposed is actually a markup, not markdown.
Maybe it's worth creating an extension to markdown that allows style classes to be defined the way you've done it, but within a syntax that's backwards compatible with Markdown (whatever that means these days(