MDX

These blog posts are written in MDX files, as noted on MDXJS.com:

"MDX lets you use JSX in your markdown content. You can import components, such as interactive charts or alerts, and embed them within your content. This makes writing long-form content with components a blast. "

This is all on top of everything that markdown already provides, here is the original cheatsheet from the tailwind starter blog

And here is a guide to using images.