First time I've come across this issue, but the iPad version of my email isn't displaying as I would expect. (I would expect it to appear as per desktop) It seems to be taking it's cue from the max-width styles and adopting the same layout as the gmail app does! It's also worth pointing out that when I send an email to my gmail account, in Chrome, both on mac and pc, it does not render as per the litmus result.
You can see the email and code here:

https://litmus.com/builder/dba1db8

Anyone have any ideas? I still need to use max-width values to help with Gmail app, but I just can't figure this out.

Thanks in advance.

Alex.