[csswg-drafts] [css-multicol] Improve column-fill and make it backward-compatible

mstensho has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-multicol] Improve column-fill and make it backward-compatible ==
Chromium, Edge and WebKit all seem to implement column-fill:auto as specified in the CR: https://www.w3.org/TR/2011/CR-css3-multicol-20110412/#cf

In particular, when block size is unconstrained, balancing is forced.

Example:
```
<div style="columns:3; column-fill:auto;">
  column-fill is auto.<br>
  Height is unconstrained<br>
  The old spec says to force balancing in such situations.<br>
  The new spec does not say anything about to that effect.<br>
</div>
```

Gecko doesn't force balancing in this case, while all the other do it. Gecko appears to follow the new spec: https://drafts.csswg.org/css-multicol/#cf for column-fill:auto. It does have issues with column-fill:balance if height is non-auto, though:

```
<div style="columns:3; height:20em; column-fill:balance;">
  column-fill is balance.<br>
  Height is non-auto, and large.<br>
  This should still be balanced<br>
  although everything *could* fit in the first column<br>
</div>
```

All spec versions require the above to be balanced, but Gecko doesn't do it. But note that if you shrink the height from 20em to e.g. 10em it gets balanced - so this looks like a bug and not deliberate behavior.

The spec was changed in 2012 by Håkon Wium Lie:
https://github.com/w3c/csswg-drafts/commit/e0a990c7e6514f95f1d0c3d6ccb08f4552365f44

Given that Gecko has bugs in its implementation, and given that all the others still follow the old spec, I think we have an opportunity to fix the new spec. Most importantly, I'd like the spec to be backward-compatible, so that column-fill:auto forces balancing if block size is constrained (and before each spanner).

If we really want a mode that never forces balancing, how about introducing column-fill:fill for that? That mode could even refrain from balancing before spanners (and only break if there are explicit breaks).

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/3224 using your GitHub account

Received on Thursday, 18 October 2018 08:48:34 UTC