[hobnail]

With purchased books, what are your goals? Mine are to not have to change the font size, margin, and line spacing sliders when I open a book for the first time. To do that I remove the class on the body tag, on any div tag that may encompass the entire chapter, and on the body p tags. (A lot of books use p tags for the chapter titles so those I keep.) Often there are span tags just inside of the p tags so those need their class removed as well. I.e., search for class="calibre8" and replace it with nothing. I've recently started removing all font-size lines from the book's stylesheet. So even that typically small text on the copyright page becomes "normal" size. I also remove all line-height lines from the stylesheet. For novels this all works well since it's mostly just paragraphs of plain text. Then at the end of the book's stylesheet I add

body {
  font-size: 100%;
  border: 0;
  margin: 0;
  padding: 0;
  width: auto;
}

p {
  font-size: 100%;
  border: 0;
  margin: 0;
  padding: 0;
  text-indent: 2em;
}

One thing that tripped me up is that if the html has 'p class="something"' and you have css for an unadorned p like mine above at the end of the stylesheet, the p with a class takes precedence, regardless of its location in the stylesheet. So you can't just add css for unadorned tags at the bottom the file thinking that they'll override stuff above. Which is why I get out the buzz saw and remove classes from the html.