Drop down (popup layer) Menu has become unreliable

[Acorn]

Before I get into Acorns dislike of my seperate menu page I've adjusted my earlier mobile example to include a 'Back' button (though I don't really see a need for this)
I've revised my earlier demo so you'll need to refresh each page to ensure you're seeing the updated version.
UPDATE

Egg, i didn't dislike you approach, it is just a Hamburger method is tedious to use: select a new page and you have to open the menu to go to another, ...

If you can always display the links to pages then do so.
Avoid Xara Buttons and NavBars, unless really vital.

Acorn