Previewing markdown files in emacs

C-c C-c l, shorthand for markdown-live-preview-mode can be used to preview the markdown file. It also opens it in the emacs web browser, so the preview can be fully inline.

Unfortunately, it doesn't appear to support callouts.

There's also a variant that renders a single HTML page (C-c C-c p).

Tip

C-c C-c shows a list of the next possible characters and what they do, though it doesn't include the full list. Would recommend looking at describe-mode as well