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multicol-margin-001 test: review comments

From: Gérard Talbot <css21testsuite@gtalbot.org>
Date: Sat, 29 Jun 2013 00:02:11 -0400
Message-ID: <c2d12e350e6fb72eb740570ab3e4512c.squirrel@ed-sh-cp3.entirelydigital.com>
To: "Håkon Wium Lie" <howcome@opera.com>
Cc: "Public CSS Testsuite mailing list" <public-css-testsuite@w3.org>



As far as I can understand, this test is supposed to be verifying that
the top margin of the first block child element of a multicol element
does not collapse with the top margin of the multicol element. Please
correct me if it isn't the case.


line 11: body {
	margin: 0;
line 14: p {
	border-bottom: 2em solid white;
	margin-bottom: 1em;

These rules are not part of the test itself. The <p> has no content
anyway in this non-self-describing test.
We usually prefer to use/rely on browser defaults for body margins and p
margins. This way, tests can be shorter and more straightforward and
they also will work on browsers with different body margins and p
There is no need in such tests for resetting those (body and p) margins.


line 19: 	font-family: ahem;
line 20: 	font-size: 1em;

Whenever the Ahem font is used, we need to set a font-size whose
computed value will be dividable by 5px without a remainer. We do this
to avoid rounding issues and to ensure accurate vertical positioning of
content on the baseline, mostly for the Linux platform.

If the test uses the Ahem font, make sure its computed font-size is a
multiple of 5px, otherwise baseline alignment may be rendered
inconsistently (due to rounding errors introduced by certain platforms'
font APIs). We suggest to use a minimum computed font-size of 20px.

And so its current associated reftest would need to be updated to
reflect this too.

All the multi-column tests submitted by Opera will need to be adjusted
on this font-size of Ahem font issue.


line 26: position: relative;
line 37: div::after {
	 content: "";
	 background: white;
	 height: 1em;
	 width: 2em;
	 position: absolute;
	 right: 0;
	 bottom: 0;
	 display: block;
line 46: }

I do not see the reason for the generated 2x1 white rectangle in the
test. If margin-top of first child collapses with the margin-top of the
multi-column element, then we will see a bright green
32px-wide-by-16px-tall rectangle at the bottom right corner. If
margin-top of first child does *not* collapse with the margin-top of the
multi-column element, then we should see such bright green
32px-wide-by-16px-tall rectangle at the top left corner. And so, the
comparison with the reftest should work by itself; the lime stripes
position and dimension would need to be identical.

So, I think that the div::after rule is not needed, not required in the
test and that line 26 is also not needed, not necessary.

As is, the test is still a correct one but it's imprecise, not
straightforward, streamlined.

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Received on Saturday, 29 June 2013 04:02:40 UTC

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