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Re: Units, font sizing, and zoom suggestion for CSS 3

From: Erik van der Poel <erik@netscape.com>
Date: Wed, 26 Jan 2000 16:10:33 -0800
Message-ID: <388F8CF9.97F33003@netscape.com>
To: JOrendorff@ixl.com
CC: www-style@w3.org
JOrendorff@ixl.com wrote:
> 
> The current SVG working draft is a little more explicit about
> 'font-size':
> 
>     "This property refers to the size of the font from baseline to
>     baseline when multiple lines of text are set solid in a multiline
>     layout environment." [1]

A teeny-weeny bit more explicit, yes. Nowhere near good enough, though.

> For computerized, scalable fonts, I think it's reasonable to say
> that this means the minimum recommended baseline-to-baseline distance--
> recommended, that is, by the font itself.

Nope. The font's recommended "leading" is separate from the font size
(height) itself.

> I feel sure that this is the
> intended meaning of 'font-size' in CSS2.  Given what the spec says about
> 'em', 'font-size', and 'line-height', this is the only reasonable
> interpretation.

CSS2 says that the half-leading is added on top of and below the font.

> Changing the definition for CSS3 is a bad idea, too.

Changing the definition of "em" may be a bad idea, but we *have* to
change the definition of font-size. It is far too vague right now.

> Suppose we decouple 'em' from 'font-size' and redefine 'em' to mean
> "the width of an M (or similarly square) glyph in the relevant font."
> Then 'line-height: 1em' will cause lines to overlap.

I withdraw my suggestion to change the definition of "em".

> Suppose we keep 'em' and 'font-size' equivalent and define them both
> to mean "the width of an M glyph".  This is even worse.  'font-weight:
> bold' would no longer widen the characters but instead reduce their
> height; the same with 'font-stretch: expanded'.

Who suggested that?

> I oppose changing the rules now.  It would only cause futher disparity
> among the implementations-- the last thing we need.

I am trying to reduce the disparity between the implementations of
Mozilla on Windows and Unix.

> The proportion of
> pedantic typesetters in CSS's target audience is not high enough to
> justify the change.  ;-)

I often get complaints about font size from Mozilla users. Font size is
a very sensitive issue. I can and will change the Mozilla
implementations, but it would be nice if the CSS spec agreed with my
changes. :-)

> This being said, 'font-size' and 'em' should be more carefully defined
> in CSS3 (and in SVG for that matter).  In SVG Fonts, the relationship
> between 'font-size'[1] and 'units-per-em'[2] should be clarified.
> 
> [1] http://www.w3.org/TR/SVG/text.html#FontSizeProperty
> [2] http://www.w3.org/TR/SVG/fonts.html#FontElementUnitsPerEmAttribute

Here, I agree completely.

Erik
Received on Wednesday, 26 January 2000 19:13:47 GMT

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