Content partly hidden behind header (data-position="fixed")

Content partly hidden behind header (data-position="fixed")

Hi :)

I'm facing the following situation: When my app initialises itself, I want to show the loading spinner and hide the first page (#main) until everything is ready.

My code hides the #main page by default (display:none) and executes the $("#main").show() after the pageshow event. But the problem is: After $("#main").show() is executed, the first line of the content is partly hidden behind the header. This problem only occurs when the header has the attribute data-position="fixed". Without it, it works fine.

Here is the code:
https://jsfiddle.net/0kdsre4c/1/

Without data-position="fixed":
https://jsfiddle.net/spqo2nou/1/

Is this a bug?

Best regards,
Falco