This keeps happening where in this forum a file is referenced that does not exist in sitefinity. It's very confusing and frustrating. You mention:
There is NO "GenericContentDesigner.ascx" file anywhere in Sitefinity.
The file "EditorCssFile.css" does exist, but it does nothing to effect the content area of a generic content control.
So I repeat my original question, for Sitefinity 3.6 SP2, how do you change the base css that the user sees inside the content area of a generic content control that they have dragged onto a page and are editing it's content?