Full height div to fixed

Question

What I would like to do is this:

Create a full height div which go to a fixed top div after scrolling.

1) -----------
   |         |
   |         |
   |         |
   |---------|
   |        ?|
   -----------

After scroll:

2) -----------
   |        ?|
   -----------

If you scroll back, you get the full height again. Or, if you click the ?, you also get the full height.

I could picture it as an extra layer which can respond with the scroll but also toggle back when the question mark is clicked.

Can somebody help me out?

Answer 1

You can just toggle a div that is fixed to the top. set it to display none by default. Make a button that toggles that div