Why is it not possible to separate the dimensions of the top position in a rectangle?

These replies don't actually work. I found a much better way, just make a null object and tie the effect position to the position of that null. When all else fails: null objects.

You can then effect the position of this null using sliders if you want and not have a brain aneurysm ok bye

Not there. Can only do that in the transform property. You should add a feature request.