Posted by Jonathan N. Little on 09/04/05 18:02

Jukka K. Korpela wrote:
<snop>
> Sorry, what Mr. Little said was wrong. Your explanation was better, but it
> did not correct the basic mistake, and was a bit misleading too. The em
> unit means the size of the font, which is by definition the height of the
> font, which is _not_ equal to the width or height of any particular letter
> except by coincidence. Roughly speaking, the height of a font is the
> vertical distance from the highest ascender's highest point down to the
> lowest descender's lowest point.
>
> The em unit means the size of the font of the element itself, except in a
> font-size property, where it means the size of the font of the enclosing
> element. How it related to the browser's default font depends on the style
> sheet(s) involved, as a whole, as well as on user actions. If you set, for
> example, * { font-size: 9px; } in your style sheet (a grossly wrong
> decision of course, but that's a different issue), then em means 9px,
> unless your style sheet is overridden by a user style sheet.
>

This may be semantics here, but 'em' from my fine arts background was
defined as the width of the capital letter 'M' of a certain font for
printing or hand for calligraphy. Therefore the em's actual size would
vary whether the font was compress, normal, demi or extended font of the
same point size. Printers would use 'em' and 'en' to describe the width
of dashes or spaces to their respective 'M' and 'N' character widths for
the font being used. Now how W3C has interpreted this for CSS I will
have to research a bit...

--
Take care,

Jonathan
-------------------
LITTLE WORKS STUDIO
http://www.LittleWorksStudio.com

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