Css classes on any block

Extensions
2

I agree and see the solution in a consistent attribute syntax, as already implemented partially by Pandoc and Markdown Extra.

A span could be done like this:

this is a [span]{.myClass} plus more inline content

While adding attributes to an entire paragraph is a bit more complicated (see the discussion in that thread) but could be something like:

paragraph
{.myClass}

I have put a draft together and made a pull request which currently includes the spans but not paragraphs.