Okay, so here’s my confusion on this. On a computer, in Cover and Fixed mode, the background image sizes to match either the height or the width of the window. On the phone and iPad, the background image sizes to the height of the body of content instead of the window making it size all the way to the bottom of the content on any given page and then still stays fixed, giving you just the top portion of the image viewable. However, if you view it in the Customizer as Desktop, Tablet, or Mobile Device, it shows it sizing the image to the window of each, not to the size of the body of content. I compared the css code to the article you sent, and it matches almost exactly except for the background-position center part of it. So it should work the same, right? I think I may be missing something obvious here. What do you think?