Update free-programming-interactive-tutorials-en.md

[sumushi]

What does this PR do?

Add resource

For resources

Description

This course breaks down the fundamentals of CSS into digestible, easy to understand pieces. Over the next few modules, you'll learn how the core aspects of CSS work and how to use them effectively in your projects. Use the menu pane by the "Learn CSS" logo to navigate the modules.

You'll learn CSS fundamentals like the box model, cascade and specificity, flexbox, grid and z-index. And, along with these fundamentals, you'll learn about functions, color types, gradients, logical properties and inheritance to make you a well-rounded front-end developer, ready to take on any user interface.

Each module is full of interactive demos and self-assessments for you to test your knowledge. In addition to learning through reading and demos, there is an accompanying podcast episode for each topic as another way to learn and continue expanding your knowledge.

Why is this valuable (or not)?

It start from beginner level concepts and goes on advanced. Byte size snippets allow easy understanding of topics

How do we know it's really free?

Well, no login nothing is required. You can visit the site and start learning.

For book lists, is it a book? For course lists, is it a course? etc.

It is a interactive course which can also be used as a reference sheet.

Checklist:

• [x ] Read our contributing guidelines
• [ x] Search for duplicates.
• Include author(s) and platform where appropriate.
• Put lists in alphabetical order, correct spacing.
• Add needed indications (PDF, access notes, under construction)

Follow-up

• Check the status of GitHub Actions and resolve any reported warnings!

[davorpa]

It's a good moment to apply some changes. When done, request for a review again using GitHub 🔃 button.

[eshellman]

well-written PR.
Thanks, and welcome to free-programming-books!