Re: Interop issues regarding tables and css tables

On Thursday 2014-06-12 20:36 +0000, Greg Whitworth wrote:
> This is a multi-part problem that I'll _try_ to explain succinctly.  We found the following an interop issue[1] where Blink/Gecko set the baseline for text in a table cell at the top when an image is included in the same row. IE sets the baseline as the height of the entire row including the image. To test this behavior further I swapped out the image with another replaced element, this time a generic iframe and now Blink/Gecko offer the same behavior as IE. I would have expected all of these to produce the same result (matching IE's behavior).

This is explicitly undefined in CSS 2.1, per the sentence:

  # If such boxes are tall enough, there are multiple solutions and
  # CSS 2.1 does not define the position of the line box's baseline
  # (i.e., the position of the strut, see below). 

in http://www.w3.org/TR/CSS21/visudet.html#line-height .  In other
words, when an aligned subtree with vertical-align: top or bottom is
present that is taller than the aligned subtree associated with the
strut for the block, then the position of the strut for the block
(and everything aligned to it) is undefined.

I think when we agreed to make it undefined in 2.1 we may have
agreed on what we wanted it to be defined as for level 3, but I
don't remember the details.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)