[css3-fonts] em unit based on used value vs. computed value of font-size

Hi,

In Font Matching Algorithm, css3-text says:

> ‘font-size’ must be matched within a UA-dependent margin of
> tolerance. (Typically, sizes for scalable fonts are rounded to the
> nearest whole pixel, while the tolerance for bitmapped fonts could be
> as large as 20%.) Further computations, e.g., by ‘em’ values in other
> properties, are based on the ‘font-size’ value that is used, not the
> one that is specified.

The last sentence is in contradiction with css3-values:

> em unit
>
> Equal to the computed value of the ‘font-size’ property of the
> element on which it is used.

I think the latter is correct: the em unit should not depend on font 
matching.

-- 
Simon Sapin

Received on Thursday, 17 January 2013 14:21:23 UTC