Is there an Applet User Property to add a certain css class to an applet?

Hi All,

simple question: Is there an Applet User Property to add a certain css class to an applet?

example: For certain applets, I want to control styling using a custom-theme.css file. However, the applets do only belong to vanilla classes like siebui-aplet, siebui-form, etc. > how can I add my custom class? I could do it through a custom PM/PR file, but it would be a complex scenario to achive an easy goal. It would be much easier by adding only a user property (for example) like "Applet CSS Class" > "my-class".

I can't find any information.

Thanks!

Benjamin