Responsive countdown timer built with vanilla JS and CSS

The CSS for the time cards was a bit messy, is there a more efficient way to do it? Also, for some reason, the radial-gradient() function for the bottom right corner of the shade isn't working properly (if you zoom in you can see it still has the faint background there) and I'm not sure why considering that it's working for the .time divs. I also have no idea how to do the card flip from middle animation lol.

Anyways apart from that, how did I go?