One thing that frustrates me beyond belief about ePub readers is that so many of them think they know better than the book's publisher about how it should look. I completely get that many people do indeed want to impose their own choice of font, line spacing, margins etc, on the book, but for heaven's sake please give us a simple "Just show me the damned book as its publisher intended it to be!" option
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I never did find an Android ePub reading app which had this seemingly simple facility. iBooks has it on iOS, but not many other reading apps do.