Not sure I get it. When you say on top of each others, do you mean the top (y) position or the layers?
Ok. let me play with it.
You cannot actually find a lower end or bottom position of an element. All you can get the height() of the box and its offset().top; position. So I guess you would have to find the height of the box and calculate the new y position with that.
- e1 height is 100px
- ie1 top position is 10px
- e2 top is e1 height + e1 top thus e1 top is 110px,
- then if the height of e1 changes to 200px, then e2 top will have to change to 210px. (e1 height plus e1 top)