Thanks for the suggestion Leanne.
In my case, this didn’t work. Still looking for help.
The background-size command might be what I need, but I think I need to fix different areas than .header-image and .site-title.
I think I must of set some size and / or position parameters for the home widget areas, and those need to be over-ridden in the media-queries sections for mobile devices. Just can’t pinpoint which ones.
Appreciate the help.
Marshall