I am looking into using sprox but I can't seem to find any information about styling the generated form. I am sure its got to be something obvious but i didn't see it in the docs or find anything using a google/google groups search. 
Ideally i would use sprox to generate the form but be able to pass in some css for layout. I could just manually create the forms but with the built in validation and select, drop downs pulling in data it seemed worth a look.
In a perfect world I would use sprox and pass it to the template and then let my designer have at it for formatting/styling the resulting widget leaving me to not have to fuss with it.
TIA!
You should be able to pass the form to the template, render it there while adding any custom css rule inside the template itself. For example using <style> tag inside the template head.
If you really want to add a custom CSS on python side you can try to add CSSLink/CSSSource to css key inside form __base_widget_args__ dictionary
Python / TG2 - Sprox