Grav/twig tutorial

I am currently studying how a theme/skeleton works. I am interested in a tutorial that shows you how to build a theme from scratch. The best one so far from my perspective is the one by Mark entitled "How to build a website in less than a week".
Are there any other in the same vein?

@antoine0579 In my opinion the Grav docs at https://learn.getgrav.org/ are a great starting point to get insight in Grav's basics and how to build themes and plugins.

The first 4 chapter will take you by the hand for creating a new theme and plugin:

1. Basics
   "Discover what Grav is all about and the core concepts behind it."
2. Content
   "In Grav, content is priority #1. Find out how to create and organize your content quickly and intuitively."
3. Themes (contains step-by-step tutorial + 2 chapters on Twig)
   "Find out how themes work and how to easily edit or create your own."
4. Plugins (contains step-by-step tutorial)
   "Grav is fully extensible with a powerful Plugin architecture to allow you to extend the core functionality and add as much functionality as you like."

@antoine0579

In addition to @pamtbaau comment i will add some ressources like

https://www.tutorialspoint.com/grav/grav_theme_tutorial.htm

and :
https://github.com/getgrav/awesome-grav

Thanks for the response; every little bit help