I wrote:
Next question: is there something wrong with SVG rendering or scaling at the moment? I've noticed that both (a) Image:Heme.svg, as seen on the [[Hemoglobin]] page, and (b) Image:NFPA_704.svg, as used in Template:NFPA 704 and seen on many, many chemical pages, are both broken. action=purge doesn't seem to be helping for these.
Never mind. Action=purge on [[Hemoglobin]] didn't help, but doing it on Image:Heme.svg and Image:NFPA_704.svg themselves surely did. Case closed. (Except for the N,000 other images that probably need the same treatment...)