Are you saying that the lines of text extend beyond the width of the screen? If so, that is rather odd because ePubs are supposed to reflow text. If you are experiencing lines of text that are too long to fit the width of the page, then the formatting of the ePub is very poor. The only thing that comes to mind is that the html from which the ePub is compiled must have the text placed in a table where the table or table column width is defined too large. Even then, I would have expected the ePub reader to overlook that formatting, but you never know. If possible, you should look at the html and/or CSS to see what is wrong. In the CSS look for a width statement within the BODY tag, and remove it if it exists. Once again I would expect the reader to ignore a width parameter, but who knows what it might do.