How do I convert leading and kerning expressed to CSS styles

Question

I have been given a design / style guide for a website that has the fonts expressed in point (pt) measurements, and additional leading and kerning adjustments - e.g. 40pt font, 60pt leading, -30pt kerning.

I would like to use em, rather than pt or px in the CSS, and am assuming (using reset) a base font size of 16px. The core font size conversation I can do, but I don't know what to do with the leading and kerning?

(PS I do know that this means the font will render differently on different devices / browsers, I just need somewhere to start.)

[UPDATE: I have created a google doc with the conversion of pt to px / em - https://docs.google.com/spreadsheet/ccc?key=0AqIQZlVb9MACdElFY1gyTS1lU3hVZFhnYWsweVM3eHc&pli=1#gid=0 ]

Answer 1

Kerning equates to .class { letter-spacing: Xem; }

Leading equates to .class { line-height: Xem; }

use the exact same conversion you are using for the font size to get the correct em values. 1pt = 1px