Responsive (on Mobile sites)

one idea is to paste the following code in CSS…

.ngg-slideshow, .ngg-slideshow img{
max-width:100%;
}

however, it does not keep the correct proportions.

What you are asking about is actually a fairly complex maneuver.

Here is a list comparing different solutions for responsive images

In order to utilize those in a sideshow, there might be a bit of extra work.

I’ve also found this. Automatic Responsive Images in WordPress.

I’ve only skimmed over it, but it is supposed to be relatively easy.

Again, I’m not exactly sure what would be involved in integrating something like this with a slideshow.