From: http://pubhtml5.com/qa/how-to-modify-the-layer-of-the-inserted-objects-with-pub-html5-digital-publication-software.html

PUB HTML5 is powerful digital publication software enabling you to convert your PDF files into stunning HTML5 digital flipbooks easily without any coding skill. You have the ability to customize and design a unique flipbook in your own style. And you can modify the layer of the inserted objects with PUB HTML5.