[css-text-decor-3] determining position and thickness of line decorations

http://dev.w3.org/csswg/css-text-decor-3/#line-position specifies
the following for determining the thickness of decorations:

  # CSS does not define the thickness of line decorations. In
  # determining the thickness of text decoration lines, user agents
  # may consider the font sizes, faces, and weights of descendants
  # to provide an appropriately averaged thickness. 

I think this "may consider" is a bad suggestion, and I would prefer
that CSS specify that descendants do not affect the thickness.

I think this attempt to determine a useful underline for a single
element is more likely to be harmful than helpful because it will
lead to underlines being inconsistent between elements.  And I
believe consistency of underlines between different underlined
elements is important in many designs.  For example, if one item
within a list (horizontal or vertical) or links contains some
superscripted text, I believe authors would expect it to have the
same style of underline as the other links.

I'm also hesitant to break invariants that you get basically the
same thing if you split a single inline into multiple inlines -- an
invariant that I expect editing tools assume in a number of cases.


I believe these same invariants apply to the rules for positioning,
where the specification is substantially more complicated.  I
disagree with the entire premise of the rules, which I think are, as
with thickness, likely to lead (in the cases where the rules matter
at all) to ransom-note style underlining, which I believe designers
dislike.

While these rules improve certain complex cases, I belive they hurt
more common cases, and they also add substantial complexity to the
specification.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                           http://www.mozilla.org/   𝄂

Received on Monday, 25 March 2013 04:39:43 UTC