[Suggestion] Settings field for background color for field-containing css class

As you can see on the demo images on the Module images it is actually possible to Change the background color value for the selector containing the fields for Media hero slider by editing the theme.

By using different Images for different sliders with different saturation and hue one backround-color for the field-containing class is not ideal, always.

So it would be great if the module can provide an option to change the background Color value by addig eiher hexdecimal or rgba values. Nothing too fancy with Color selector or even Color Wheel. just an Input field to define a Background color value per slide.