Mobile first with Flexbox and vanilla JS

Hi everyone!

Please feel free to comment my solution and let me know if I can improve my code. Please have a look at javascript part and let me know if it can be written differently or if there is something that can be improved (really appreciated!). If anyone knows where to read more about how to enable submitting the form after user clicks submit button - at the moment I used e.preventDefault() to stop form from submitting.

Thank you!

PS. I updated accessibility issues but somehow I cannot generate new report... If someone can check if I done it correctly I would be thankful!