The image cannot be displayed, because it contains errors
Seems Firefox was complaining because some of the .jpgs Duende sent — which I was trying to add to the site — were in CMYK (print) instead of RGB (screen display). Makes sense. Duende’d sent the photos used in prior years’ brochures.
Turns out ’tis simple enough to pull the .jpg into Photoshop. Go to the Image pulldown menu IMAGE->MODE and save the JPG as RGB instead of CMYK.
And Bob’s your uncle.
Would that most of the world’s problems were so easily handled.