Order Summary Component with HTML, CSS, & Flexbox

Hey everyone! I just completed this project and I know my code is really sloppy and I'm sure it could have been written in a more organized way, I just believe that the best way for me to learn is to dive in and apply anything that I know, so that's what I did.

This is the first time that I use flexbox in a project and I'm still not really sure I understand it fully, so I'd really appreciate if you point out any mistakes I have with it specifically.

Again, I'm only a beginner and I know there is so much I don't know yet, so any suggestions or tips to improve the code overall would be really appreciated. Thanks!