In the last few months I've worked on creating Codedraft, a mobile application that allows you to learn CSS. It is currently available on Android only:

https://play.google.com/store/apps/details?id=com.codedraft

The main idea of the app is to learn and practice at your own speed, that's why the information is split into very small pieces. It offers two courses, CSS Basics and Advanced CSS, each of them being split into several sections.

Another feature of Codedraft is the ability to practice what you learn in the web app, available at https://app.codedraft.io. When learning in the mobile app, occasionally you have the option to scan a QR code on the web app - this action will automatically take you to a relevant coding exercise.

The web app can also be opened from the "Scan Code" tab in the mobile app.

I've always wanted to work on an educational software, however this is my first dive into the domain. :) I would be very happy to get any type of feedback possible.

Let me know if you have any questions and thanks a lot for reading!