Create a table position fixed inside a div collapse

问题

I have a special request, click here. to look the case.

Once I click over the arrow down and the div collapses, I need to make fixed the first table in the div collapsing and making scroll the other table below.

I hope the explanation is clear. How would you achieve that?

来源：https://stackoverflow.com/questions/12109677/create-a-table-position-fixed-inside-a-div-collapse