Making an element "fixed" if it's being scrolled out

Question

So, I have an element on a webpage that is located under some other elements. This element should, whenever it hits the top of the page be fixed (ie. it shouldn't leave the view.)

I've seen this being done on the Webkit Inspector in the resources tab.

Does anyone know how to replicate this feature/effect?

Answer 1

I think that the behavior you want is similar to the desired on this question, check this example.