Hello Brandon,
Actually it’s a bit difficult to achieve a total responsiveness for background images without compromises. I suggest yo to try out having two different sections, one for mobile and for desktop and set the properties accordingly. And under Customize > Hide During Breakpoints you can hide the section depending on the screen-sizes. https://cl.ly/2B3M3C09013M
You can take a look at following page to learn more on how background image works:
https://davidwalsh.name/demo/background-size.html
You can also try out following solution. First set the background size to Cover. After that, In the first section (https://cl.ly/282O1m0g2P17) add a custom Class under Customize > Class https://cl.ly/1W0y1h1z0d3f. After that add following CSS under Pro > Theme Options > CSS:
@media screen and (max-width: 890px){
.custom-class .x-bg-layer-upper-image {
background-size: contain!important;
}
}
You can replace class name as per your requirement.
Let us know how it goes.
Thanks.