This is my first try at using picturefill (http://scottjehl.github.io/picturefill/#using-picture
). The markup seems pretty simple, but the images do not respond to resizing the viewport. It appears the code selects the correct image for the initial size of the viewport when the page is loaded, but the images do not respond to subsequent viewport size changes.
If anybody can see what is causing this, it would be greatly appreciated.