squarespace 7.1 CSS so video shows only on mobile

Site URL: https://dandelion-lily-gln7.squarespace.com/config/pages/5e8638822b23774bd980f66a

Hi. I have a site that has a great background video. 

Maharry.work.  Pass is Leo

My problem is that the background video does not play on mobile. 

So, my ingenious solution is to include a regular video just under the banner video. This will include the same video, and overview of my work, that is in the background video. 

To make this work I need CSS to 

1. Suppress the background video on mobile

2. Allow the regular video to display on mobile, with it's "play" button, and suppress the regular video on desktop and tablet. 

Can you help? Anyone? Beuller? Thanks in advance!