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Re: [css21] line-height, problem?

From: Alan Gresley <alan@css-class.com>
Date: Mon, 26 Nov 2012 21:00:27 +1100
Message-ID: <50B33DBB.90506@css-class.com>
To: Andrew Fedoniouk <news@terrainformatica.com>
CC: www-style@w3.org
On 26/11/2012 6:21 PM, Andrew Fedoniouk wrote:
> This sample:
> https://dl.dropbox.com/u/14981836/line-height-test.htm
> contains two identical paragraphs, the only difference is that
> first one has line-height:normal and second one - line-height:1em;
> According to the spec [1]:
>     'line-height' specifies the *minimal* height of line boxes within
> the element.
> If that property defines minimal height then these two paragraphs
> should be rendered in the same way.
> --
> Andrew Fedoniouk.

Not so. The minimal height for line boxes is depended on the font used 
(Times New Roman is different from Georgia). With line-height:normal 
(which is the default), each line box is layered out so no line boxes 
overlap. With Latin Script, each line box will enclose the letters with 
acutes and the lowest descender (the Greek letter Xi ~ ΞΎ).

A test case [1]. A tool [2] that shows the different between aspect 
ratio (for x-height), line-height and span height of commonly installed 
fonts. The historic typeset baseline that has made it's way into the 
modern web [3]. Another test case [4] which shows how line-height:0 
works with floats. This is where various browser diverge greatly.

1. http://css-class.com/test/css/text/linebox-line-height-011.html
2. http://www.brunildo.org/test/aspect-lh-table2.html
3. http://en.wikipedia.org/wiki/Baseline_%28typography%29
4. http://css-class.com/test/css/text/linebox-line-height-012.html


Alan Gresley
Received on Monday, 26 November 2012 10:01:03 UTC

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