I am using markdeck with vim. Markdeck has an auto-reload, that means, every time you save your markdown or change something in your assets-folder, the web view gets reloaded automatically; so not really live preview, but auto-reload on save...

And markdeck has a standalone-exporter: it generates a single html file with all resources embedded (url-data, base64, ...); one file to send/open/view, but with working animations and the like (even the terminal session works)