NFT Preview Card [Plain CSS]

Hello there fellow devs! I have finished the NFT Preview Card, I tried making it as responsive as I could, and I wanted to make a glassmorphism effect this time, but couldn't figure out a way to make it responsive, the background-image I put in did not want to cover the whole body, as a matter of fact my body / html weren't stretching 100% height even if I set them to 100% height, tried googling but just couldn't figure it out. Maybe its because I put rem's everywhere? Maybe that's not the best way to make it, but I will leave it up for you guys to give feedback and I will most certainly be glad to read it and implement them!

Thank you! ^-^