Just wow. This is an impressively hacky hack. You’re probably wondering how? As many such things do, it all starts with a new (Chrome-only) API:

A new set of APIs affectionately known as Houdini give your browser the power to control CSS via its own Object Model in Javascript. In English, this means that you can make custom CSS styles, add custom properties, and so on…

And it ends with something that looks like this:

main {
  // ...
  --sql-query: SELECT name FROM test;
}