Firefox has a very usefull tool when working with layers. It allows you to view a website layer by layer in order of display. I found it most usefull when setting z-index in style sheets to set which elements go on top and which go under. This is quite an easy tool to use. Here I will show you a quick example on how to make full use of it. First visit http://www.google.com to follow each step. Make sure to use Firefox as a browser.