With some coaching on the IRC, I got this working.
The trick, it appears, was a combination of using this Injection Selector: L:(text.html.markdown $)
along with this rule set (only markup.raw.* are important here):
{ patterns = ( { name = 'source.yaml.front-matter'; begin = '\A-{3}'; end = '-{3}'; patterns = ( { include = 'source.yaml'; } ); }, { name = 'text.html.markdown.classes'; begin = '{'; end = '}'; }, { name = 'markup.raw.block.markdown'; begin = '^`{3}'; end = '^`{3}'; }, { name = 'markup.raw.inline.markdown'; begin = ' `'; end = '`(?=[ .,;-=+])'; }, ); }
Bob ------------------- Robert J. Rockefeller Richmond Hill, GA www.bobrockefeller.com