Well the content is stored in a DNS Zone file but it is requested using JavaScript to an external HTTP API. I wouldn't really call that HTML over DNS but rather "DNS Zone as blog database".
Anyway, this made me think of iodine [1], an IP over DNS solution, which I still run on my main server even though it has a lot less use now than it had until a few years ago when there were a lot of open wifi with captive portals and way less 4G available.