The short story is that recent Android versions can set a systemwide color tinting theme based on your wallpaper. The Stephanie wallpaper I tooted last sets that color as purple. Except, I only set it on the lock screen (not the home screen), and that's overriding the color from the home screen's wallpaper. That doesn't seem right.

Thus, in the interests of testing, I decided to make a yellow-prominent wallpaper. I'm going to need a green one next.