Images not overlaying AND not responsive (mobile)

The images do not overlay. They first display one on the upper-left and the other on the lower-right. The slider makes one bigger and the other smaller depending on which way you move the slider.

The issue seems to be the theme’s CSS
#primary img {
height: auto;
max-width: 100%;
}

I corrected that issue by using this in my custom CSS panel:

.juxtapose .jx-slider .jx-image img {height: 100% !important; max-width: inherit !important; }

The slider is not responsive—it does not resize for mobile.

Any ideas for a fix?

https://www.ads-software.com/plugins/slider-comparison-image-before-and-after/