Ha! Silly me, after all my painstaking efforts to make sure that I'd made all the corrections/changes I'd wanted to, I just realized that I'd forgotten to change the viewbox/image dimensions for my full-page SVG images from 600x900 to 1200x1800. I just fixed that up, though, and re-loaded my book (in my original post). Pardon the oversight, but at the same time I don't think it was too drastic an error, and shouldn't have affected how things looked all that much in any really noticeable way in the first version.
