After some more research and with trial and error I've gotten closer:
.sqs-mobile-info-bar-trigger {
background-color: silver !important;
}
This changes the color of the boxes under the icons, but it's fulltime; I just need to constrain it to active only, whatever the correct nomenclature is. I don't know why squarespace is so secretive about this.
Any ideas from the experts appreciated. Thanks!