What does 12px/13px do in css font declarations? [duplicate]

Question

Possible Duplicate:
What does this CSS shorthand font syntax mean?

I saw many people doing that:

body {
font: bold 12px/13px Arial, Helvetica, sans-serif;
}

What is this 12px/13px for?

Answer 1

12px is the font size and 13px the line height.

Example of declaring all font properties in a one liner here.

---

All this being said, I'll just add that this is a pretty unusual way of writing it and I wouldn't recommend it since it might confuse most developers.

Answer 2

The 12px is the height of the font in pixels. The 13px is the height of the line in pixels.