We utilize Slideshow Pro for our galleries and slideshows on our website. It's Flash based, but the neat thing about it is that it's able to show a non-Flash version called a "mobile poster" which links to a swipeable gallery for iOS and Android devices.
The bad thing is that when our responsive site scales down for one of these mobile devices and the mobile poster replacement takes over, it's breaking the bounds of our #Content DIV.
I've found that the DIV for the mobile poster is #album-5, but all efforts to make length & width 100% instead of the set number displayed has failed.
You can easily replicate the problem by making the user agent for your browser iOS, and then shrinking the webpage until you see the error.