Pixels vs. Points in HTML/CSS

Question

When creating an HTML page, should I specify things like margins with pixels or with points in CSS?

Is one of them considered to be better practice than

Answer 1

Anybody who tells you to use pixels is wrong. Pixels work fine, but they are simply not required... Ever! Points are a perfectly fine way to specify an absolute measure, and for the scale we are commonly working at on the web they are more often then not the preferred measure.

Beside points, there is also pica, inch, centimeter and so forth. Choosing one of these over the other is a lot like saying, "should I measure this room in feet or inches?" Let common sense be your guide. They'll all get the job done.

Em, which came up in some of the answers, should be reserved for when it's appropriate. That is to say, "when this thing scales, I want this other thing to scale". That's what relative measures are for. I know that is beyound the scope of your original question, but I had to address some of the nonsense about "always using em".

BTW, pixels don't equal physical pixels. Today, px in a stylesheet means 1/96th of an inch. This is why I say don't use them. Most people don't know this. They use them thinking they're specifying actual pixels. I can't take these people seriously with this being apparent (Although I don't blame the people, I blame the confusing nature of the state of things which is why I campaign for pixels to disappear.). Furthermore, if pixels really meant pixels, they'd be a horrible way to specify dimensions. Talk about the fact that things would randomly shrink and grow based on uncontrollable arbitrary screen resolutions. Yikes! Stay away from pixels!!! In practice they work, but only due to fudging an unseen efforts on the part of browser makers and OS folks, in theory they're a horribly ambiguous way of specifying your intentions.