mdBook is my favorite tool for creating on-line docs. I wouldn't use it to create a printed book or a PDF, etc., but quick static documentation in HTML it work

mdBook is my favorite tool for creating on-line docs. I wouldn't use it to create a printed book or a PDF, etc., but quick static documentation in HTML it works quite well. It's simple and robust and just works; and most of the limitations are due to Markdown rather than to mdBook. If I could wave a wand and extend it in any way I chose, I'd want the ability to implement macros (or the equivalent) a la TeX, so as to automate doing fancier formatting in HTML.