My four e-books are now free of auto-hyphenation and other problems mentioned in this thread!
The solution was both simple and perplexing. I just added this to the ePub CSS:
Code:
body {font-family:"Bookerly", "Caecilia", serif;}
There is no font specified for main text otherwise (only titles and chapter headings), and the reader can still select their preferred paragraph font from the device's font menu, which is important to me.
For chapter headings and titles,
{font-family:"Helvetica", sans-serif;} worked, but I later embedded fonts for those.
In the past, I did not specify a body font at all. This was never a problem for files I'd uploaded prior to mid-February 2015, but after that time the omission caused the following problems on several devices (Fire HD6, Fire HDX 8.9, and 2013 Fire HD7):
- Auto-hyphenation
- Darker, less crisp fonts
- Smaller, fuzzier chapter graphics and author photo
It feels SO good to have my books appear the way I intended again! I hope this information will help someone else.
I thank you all for your patience and generous assistance. Your efforts were truly appreciated!