Gunlaug Sørtun wrote (among other good bit of advice):
>For cross-browser compatibility year 2005: rewrite all 'font:....' so
>font-sizes are defined in 'em' or '%', and line-heights are in 'em', '%'
>or 'unitless', as IE/win can't resize fonts defined in px-units.
There are very few use cases that require
line-heights with units (indeed, I can't even
think of a single one). I would strongly
recommend that you use unitless line-height
values as a matter of course. Only if you are
dead sure that you want the COMPUTED value of a
line-height to inherit should you use a unit
value. Using units on line-heights is a very
common way to break a website.
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