I added Template:Gravid_About to include a page, and included them through iframe in a normal html page: TestPage.html. The result is not as expected, the inclusion still shows header and footer. I had expected to see only the text
I have now tested in Opera, Vivaldi, Chrome, and Safari.
All of them have the header with them.
Mac OS issue? - I can't believe that the OS affects the view in the browser.
Have I forgotten something in the Wiki as packages?