The code blocks in this article are not captured in the Push to Kindle rendering: https://shortn0tes.blogspot.com/2017/06/how-to-use-platformio-to-develop-for.html
Hi Harry, Push to Kindle currently does not support content which relies on Javascript to render. In this case, the code blocks rely on Javascript to display. If you try disabling Javascript in your browser you will see that those code blocks do not appear.