We all know now that the new "peek and pop" feature of the iPhone 6s mail app counts as a email open. This means that images and HTML are donwloaded to produce the preview. However, does anybody know how this works behind the scenes? Is the "peek" going to show the desktop version or the responsive version?

In this case, is the app taking a screenshot of the HTML, or is the "peek" view and actual live rendering of the HTML with images?