I have generated my own tiles for part of the Great Britain using the osm.pbf file from here  and the style sheets from here .
I'm using Mapnik version 3.0.9 and generating the tiles using the polytiles.py script from 
As I understand it the OSM website uses the same style sheets but my tiles don't look the same as the OSM ones. For example, the road colors are different and some road labels don't line up between tiles.
OSM Screen Shot
My Tiles Screen Shot