02. Learn about DOM and CSSOM - Gr0mi4/Hello-World GitHub Wiki

This is an extremely useful article to learn about internal mechanisms of a browser. Critical for a good understanding of how everything works.

https://developers.google.com/web/fundamentals/performance/critical-rendering-path/constructing-the-object-model

You can switch to Russian language (see the button at the top of the page) if it seems too complicated.