well the first main thing to address is the size of your mobile layout. You might want to check your size on your container class in mobile view it is 940px wide when I removed that it helped things. But not sure if you did this challenge mobile first or desktop first. It might be good to start this challenge again mobile first and take what you have learned and reinforce you learning trying to improve on what you have done so far
also you need to check your border radius on your cards