Vanilla JS site using CSS and Flexbox

This is my first Junior level challenge and I was very challenged with this one. I started with html and css before proceeding with the interactive part. It took me a very long time to complete this challenge but it's all worth it.

I will be gladly hear your feedback for this.

Also, I am thinking to start learning SASS, React or any CSS, and JS related frameworks but I don't know if now's the right time to learn them. I would like to know your opinion regarding this. Thank you so much! Happy coding!