Edit Form / Edit Design
It looks like when I select a form made with Form Builder and the click on Edit Form to change something and later on click on Edit Design that the software is loading the default CSS and overwrites the current set. Have you encountered this too?
Also when I open Edit Form and change something in "Customize CSS" and do not click on the "Apply" button but just on the "Finish" button nothing will be saved. That's confusing ...