Setting CSS in a Derived Widget

[cecashon aol com]

Is there a way to add CSS property functions to an external widget? For example, if you create a simple widget outside of the GTK main build can you add a couple of functions that will accept a CSS string and set the values? I put together a simple stepped progress bar widget

https://github.com/cecashon/OrderedSetVelociRaptor/tree/master/Misc/SteppedProgressBar

and don't have that part figured out. New at deriving objects with glib as well.

Another related question. At what GTK version does the CSS string syntax change? If I check for the version and supply the correct string is that an acceptable way to write code that is compatible with all GTK version 3 builds? There is a test program called stepped_progress_bars.c in the above folder that shows the start of what I would like to do which is be able to supply a CSS string to the stepped_progress_bar widget and be able to set the initial color properties.

Thanks,
Eric