I always start every css with:
Code:
* {
margin: 0;
padding: 0;
}
to get rid of any possible default margin settings.
Although I never use page numbers, I always DO use a body margin of 1% to keep the text from colliding to the e-reader display sides, hence allow a better reading experience. Further margin needs are set, where appropriate, with <p>, <blockquote>, etc.
Just my 2cts...