when element contents flows from previous page bottom to next page top, calculated progression is based on bounding box top edge, wrong offset, going backwards #33
Also: progression 100% based on mouse click (element position in document flow) is limited to body actual length, does not include padding blank whitespace at end of document.
Also: progression 100% based on mouse click (element position in document flow) is limited to body actual length, does not include padding blank whitespace at end of document.