Allow different background-size property values for each breakpoint when using Responsive Background Images Formatter

Allow different background-size property values for each breakpoint.

It would be a nice feature to be able to select different property values for each responsive breakpoint. An example would be use the value “background-size: cover” for desktop breakpoints and “background-size: contain” for the others.

In order to accomplish this now I just add CSS code for each of my breakpoints in my theme.