I am currently building a site from a PSD. Most of the fonts have a letter-tracking of -25 ( <- AV-> : I'm guessing that is the symbol for letter spacing?).
How would I get the same effect in CSS? I know the property is letter-spacing: X but it doesn't take percentages and -25px or pts would be a huge figure!
You can use the em dimension instead of px, thus sizing the spacing relative to the font size (so photoshop's 25% is somewhere around .25em).