That's an almost full static website made out using the Astro framework. The only JavaScript that it contains is on the post page that lets people copy the code snippets from the pre tag, besides that, once it's built the website is script free, so to say.
You can check the repository here and follow the guide Astro provided to make your own blog using the framework. Note that if your goal is to achieve this same website, Astro's guide might lead you to a different result though it may look similar.
First impressions using Astro framework.
The Python HashMap.
Python List.
The way Strings are seen in Python.