Four Card Feature Project

This project was really fun to do and it tested my grid knowledge. One aspect that took a decent amount of time is playing with the box-shadow properties. If anyone has any good resources to practice/learn box-shadows in css please let me know! Also this is the first time I've used the ::before css property to get the colors on top of the containers. Please provide any feedback to improve my code in any way, including the box-shadow and ::before situations. Thank you in advance!