I noticed that on the magnific popup description page http://dimsemenov.com/plugins/magnific-popup/ the pop-up images come with an inline element of max-height (e.g.610px), while on my implementation the the same element on the same screen displays max-height as 7241px - obviously the document height -, which leads to a wrong display of img height. Certainly I can force this with the img.mfp-img tag and set max-height, but I don't consider this the right solution. May be I am overlooking something and asking just a stupid question. So far yet I could not find a solution.
And as a second issue while the pop-up images display well on Android mobile in portrait mode - again the image height issue occurs again as soon as I turn the device to landscape i.e. images are not fitting. This does not happen on the description page http://dimsemenov.com/plugins/magnific-popup/ - instead the window height seems always read out correctly. I guess this is again related to my first in img.mfg-img.
Please someone help me to understand my stupid mistake - thank you.