Re: vertical-align and line-height

On Feb 26, 2009, at 1:17 PM, L. David Baron wrote:

> On Thursday 2009-02-26 13:09 -0600, David Hyatt wrote:
>> Where is it specified that the half-leading should be included when
>> doing text-bottom/text-top alignment?  I couldn't find this in the  
>> spec.
>> If a font can be thought of as being broken into half-leading +  
>> ascent +
>> descent + half-leading, then WebKit is currently aligning to the  
>> top of
>> the ascent when text-top is specified and the bottom of the descent  
>> when
>> text-bottom is specified.  Is that wrong?  The result in WebKit makes
>> more sense to me than what I'm seeing in Firefox and Opera.
>
> The definition of the value says:
> # text-top
> #   Align the top of the box with the top of the parent's content
> #   area (see 10.6.1).
>
> So this says to use the text metrics of the parent, but the "top of
> the box" for the child, which includes half-leading for non-replaced
> inlines.
>
> Given the changes that we've made in CSS 2.1 (in which 10.6.1
> defines the height of inline boxes in two different ways), I suppose
> one could actually argue this is ambiguous, but if so I think it's
> clearer in REC-CSS2 and that was an unintentional side-effect of CSS
> 2.1 editing that we should perhaps clarify.  That said, I think it's
> still pretty clear, since throughout section 10.8 "height of the
> box", etc., refer to values with half leading.

Is this the half-leading that is intrinsic to the font, or the half- 
leading according to specified line-height in CSS?

dave
(hyatt@apple.com)

Received on Thursday, 26 February 2009 19:21:21 UTC