What font set does Apple use for main body text

What font set does Apple use for main body text on http://www.apple.com/mac
I am refering only to the smaller text such as ....
"Leopard has over 300 amazing new features. But most impressive, it just works the way you want it to."

Is it: <font face="LucidaGrande, Geneva, Arial, Helvetica"> ???
I can't tell from the source code! Would like to use same font hierarchy for my website.

Why have they expressed the font size as a fraction 12px/18px ?
When I copy and paste the text from a browser into Word, it seems to be 11px.

thanks angelwatt : )