That is something that I learned about a few days ago doing the Dreamweaver lessons.
This is how the book had me do it in the stylesheet instead of doing it inline.
Code:
h1, h2, h3, h4, h5, h6, p {
margin-top: 0; /* removing the top margin gets around an issue where margins can escape from their containing block. The remaining bottom margin will hold it away from any elements that follow. */
padding-right: 15px;
padding-left: 15px; /* adding the padding to the sides of the elements within the blocks, instead of the block elements themselves, gets rid of any box model math. A nested block with side padding can also be used as an alternate method. */
}