It is designed to be read by looking at the theme HTML which is heavily commented. The easiest way to do that is by looking at the source on GitHub.. Otherwise this is just a demonstration that the theme is fully functional.
This is a very basic theme for MkDocs with the goal of demonstrating all of the features with minimal HTML and CSS.
If you want to use this theme as a base to create your own, it is best to download or fork the theme and start to modify it
Make sure you read the MkDocs documentation regarding writing custom themes.