You need to set the css left/top as @czarchaic mentions, but rather than just setting to 0
you need to set to the drop position using ui.offset
of the dropped element, and then take into account the offset of the drop zone, padding, margin and border widths.
x.draggable({
helper: 'original',
containment: '#droppable',
tolerance: 'fit'
}).css({ top: ui.offset.top-6, left: ui.offset.left - 228});