Flexbox and JS simple concepts

One way to check that you are progressing and have understood the concept is to review the code written by other. This way you can not only test your understanding of concepts but also learn new techniques stuff. Most of time, you will be trying to improve the code that is written by other or submitted to you for optimization. Also, it would mean so much for me as well to find my weak points, flaws and suggestions through your reviews. So would you take a moment to review the code, please? Thank you even for reading this.