epub fonts

A person reading a book of mine is complaining they can not resize the fonts on their reader, which uses epub documents. My reader uses mobi and I can resize the fonts. This person says all of their other epub books can be resized.

Is this a known thing?


I’m having the same problem. In fact, just posted the same thing yesterday. However, no responses yet. Still waiting. I can’t figure out a solution. I had the same problem when I used Sigil to create epubs.