In the interest of a consistent baseline, you should give paragraph element a bottom margin that is equal to the line-height. Here is an article I wrote on the matter that goes into more depth: http://joshnh.com/2011/08/03/how-to-set-up-a-baseline-grid/
I prefer a margin-bottom that's 2/3 of the line height; say 16 and 22, resp. But then, I don't really use grids -- in that case, a full empty line makes good sense.
Which goes to show that it's really all personal preference. :)
I usually just add something that I think looks good. It all depends on the context and the font; sometimes I want a large visible space between paragraphs, sometimes only a small difference that isn't very noticeable.
@lpeabody I've been lately experimenting with percentages and no bottom margins with exception of paragraph. If I want my base font pixel size to be 16px I leave body font size attribute at 100% And if I want my base font size to be 14px all I do is change font size at body level to 87.5% Something like this:
* { vertical-align:baseline; font-weight:inherit; font-family:inherit; font-style:inherit; font-size:100%; border:0 none; outline:0; padding:0; margin:0; } body {font: lighter 100%/1.6 sans-serif;} /* font styles ------------------------------------------------------*/ h1, h2, h3, h4, p {margin:0 24px} h1 {font-size: 300%;} h2 {font-size: 180%;} h3 {font-size: 140%;} h4 {font-size: 120%;} p {font-size: 100%;margin-bottom:3.3%;} strong, b {font-weight:700}
Which goes to show that it's really all personal preference. :)
-- Richard Rutter's "Compose to a Vertical Rhythm"
-- Wilson Miner "Setting Type on the Web to a Baseline Grid"
You may also want to check out the following two sections of The Elements of Typographic Style Applied to the Web, a "webification" of Robert Bringhurst's book of the more or less same name:
2.2.1 Choose a basic leading that suits the typeface, text and measure
2.2.2 Add and delete vertical space in measured intervals
It all depends on the context and the font; sometimes I want a large visible space between paragraphs, sometimes only a small difference that isn't very noticeable.
I've been lately experimenting with percentages and no bottom margins with exception of paragraph.
If I want my base font pixel size to be 16px I leave body font size attribute at 100%
And if I want my base font size to be 14px all I do is change font size at body level to 87.5%
Something like this: