I think the reason this is happening, is because by the item sliding up, the page height is getting shorter. Firefox can't redraw the page, change the height, scroll the viewport up, and animate your element all at the same time.
JQuery tries to do too many things at the same time, and in the process, it is cutting corners, doing illegal things. For example, while getting the dimensions of an element, it actually updates it. It is not a bug in FireFox, it is a bug in jQuery.
You can see it here.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.