Hidden fields move visible fields down when hidden fields are visible

Hello,

I have a form that I have a couple of hidden fields on. If the user choses a specific choice from a dropdown, the field(s) become visible. The question I have is how do I make it so when the fields are invisible the visible fields are close together, and then when a selection is made to make one or more of the invisible fields visible the rest of the fields below it move down to make room?

This is how it is:

field 1
[space for hidden field]
field 2
[space for hidden field]
field 3

This is how I would like it on load:

field 1
field 2
field 3

And if a selection is made from field 1:
field 1
[hidden field visible due to selection in field 1]
field 2 moved down to make room for hidden field visible from field 1 selection
field 3 moved down to make room for hidden field visible from field 1 selection

Thanks in advance for any assistance!