plugin’s logic please

Hello there, first of all thank you for making this plugin available for free.
I’m testing it but I need to understand how it works. Does it rely on the screen resolution or does it detect the sys op running on the device itself? I’d need to replace some pages that use a parallax effect (it doesn’t work properly on android devices) with other “static” pages. So I’m in need to detect the sysOp instead of the screen resolution. Could you help me? Thanks in advance.