3-column preview card component solution

I would like to gain any feedback regarding this project. I would have to say I took the most time getting the website to be as responsive as possible and the media queries were a bit of a challenge. Aside from that, I would also like feedback regarding my code in general (any changes I could have made, anything I could have added/left out, structure, etc).

Overall, for being my first CSS Project without assistance, I'm happy to have completed the project. However, I definitely need input to continuously improve for future projects.