CSS for slideshow background in 7.1 ?

Site URL: https://www.museumofplayandart.com.au/

Hi guys, can someone please help me with a simple CSS query? Thank you so much, in advance!!

What I'd like to do is 'flick' between multiple images for a background, using squarespace 7.1. Currently, it's limited to a single image or video for the background.

Right now, I have a video creating the effect I want, but the resolution is terrible and there isn't a resolve to this issue using squarespace - yet. Trust me, I've been to the bottom of that well, looking for a solution and squarespace themselves have chimed in to advise there is no way to force embedded video backgrounds to play in high res.

And so.......  to get the same effect as the video, but in high res, I figure I'll just use good quality images and use custom CSS to flick between background images. But I don't know what code to use - please help :) THANK YOU!

Site is https://www.museumofplayandart.com.au/