Given that it's not that old, and it's still actively used I wonder why people never include it in the list of recent Common Lisp code bases, for new users to take a look.
It's always the same recommendations.
Until now, the source code published on GitHub has usually been a few versions behind the live website running at https://mathb.in/ but I am hoping that in future, I will keep the source code on GitHub as recent and as updated as possible.
The process of the rewrite was roughly like this: simplifying HTML, CSS, and JavaScript code first, then switching from MathJax v2 to MathJax v3, then making corresponding changes in the JavaScript code, then replacing the custom Markdown + LaTeX demultiplexing logic with TeXMe that is specifically designed to solve this problem, and finally rewriting the server-side functionality in Common Lisp. The last activity had roughly six phases of development: writing some of the utility functions I would need later (e.g., parsing posts, storing/retrieving posts, etc.), writing tests, presenting the home page, processing the post submission, presenting post pages, and performing post validations.