code: function getPaddingRectRoot( elem ) {
  
          var rect = elem.getBoundingClientRect(),
              props = getCss( elem, [
                  "borderTopWidth", "borderLeftWidth"
              ], { toFloat: true } );
  
          return {
              top: rect.top + props.borderTopWidth,
              left: rect.left + props.borderLeftWidth
          };
      }
docs: Returns the top, left coordinates of the rect of the padding box (offset box).
  
  The coordinates match those of getBoundingClientRect, but exclude the borders.
  
  Does not care about bottom, right coordinates, in order to speed up the process.
  
  @param   {HTMLElement} elem
  @returns {{ top: number, left: number }}