I hope this screenshot (of my blogpost) demonstrates the problem well:

This happens because of concatenation here:

Current behavior: Append posts list to the post Markdown file, then run pandoc, then append header and footer
Expected behavior: Run pandoc on the post Markdown file, then append posts list, then append header and footer

loosely related to #10

PS My header.html and footer.html are empty files. I use pandoc templates instead. See my template and my generation script