Neal <ne*****@yahoo.com> wrote:
Question: if -0.2ex might be rendered differently, wouldn't -0.1em
yield more predictable results, and therefore be more desirable?
More predictable, yes; but not necessarily more desirable, if -0.2ex
describes better what you really want.
Especially when the actual pixel height of 1em would be under 20px,
the actual center of the ex-height wouldn't vary more than a pixel...
In this particular case, dealing with a specific character (which IMHO
should not be used instead, since it is a punctuation mark [sorry for my
typo "markup" in my original reply]), it seemed, after some quick tests,
that -0.2ex might be close to the desired appearance. I tend to think
such things in terms of the x height, and therefore used the ex unit. In
this case it would indeed rarely matter whether one uses -0.2ex or
-0.1em. But I think that typical when you set the vertical-align property
for a piece of text (e.g., for <sub> or <sup> elements to get a more
consistent appearance), ex better relate to the goal. For example, to set
some character in a suitable superscript position, I would rather
describe "suitable" in terms of the x height than the font height.
--
Yucca,
http://www.cs.tut.fi/~jkorpela/