The four smaller images in the infobox peek out more to the right than the two wider images above and below them.
Topic on Talk:Reading/Web/Projects/Print Styles
Which infobox where (also, probably a known problem, that we also see on mobile, hard to fix).
Ah no, this is due to the cell padding of tables:
padding: 2px 5px !important;
Hmm, I don't see why we would add !important there.. Seems dangerous to me to have that on such generic elements. If anything it should be .infobox > * > td in that case.