Is this what You are trying to accomplish? Demo.
Project file: CustomCursor_JHSv1.hype.zip (18.9 KB)
In the CSS "style" tag (in the Project's "Head HTML" tab) the "body" is set to a custom cursor, as well as two of the squares (whose class is set to ". customCursor" in the CSS). You set the "class" for an element - such as the squares - in the "Identity Inspector". Do NOT include the "." (dot) when entering a class name in the "Identity Inspector". It would be just customCursor - as per my Project file.
The blue square is set to the pointer cursor in the "Actions Inspector" - just for variation.
"Head HTML" tab