string, defaults to 'center', can also be: 'top-left',
'top-right', 'bottom-left', 'bottom-right',
specifying the origin from which to "grow" the element
Either 'box' (default, scales the visible area of the element)
or 'contents' (scales the complete element, that is parts
normally only visible by scrolling are taken into account).
integer value, either the new absolute target of the effect
elements left value or the modifier of its current left value,
depending on the mode option