[csswg-drafts] [css-break] Tall unbreakable content - overflow or slice? (#4509)

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

== [css-break] Tall unbreakable content - overflow or slice? ==
When we have truly unbreakable content (such as a line, an image or a border) that's taller than the fragmentainer, we can generally do one of two things: either slice it into multiple fragmentainers, or let it overflow the fragmentainer, in the block direction. I can't find this clearly specified anywhere. Seems to me that for printing, for instance, we want slicing (or content would be lost). For multicol, on the other hand, just letting it overflow the column seems appropriate. Gecko does that, Blink doesn't.

```
<div style="columns:3; height:100px; column-fill:auto; background:yellow;">
  <div style="border-top:150px solid hotpink;">
    line 1<br>
    line 2<br>
  </div>
</div>
```

There's really only one (class A, B or C) break opportunity here - between the two lines, and Gecko does exactly that. It puts the entire border plus the first line (even if it's too tall) in the first column and the second line in the second column.

Maybe each spec that uses block fragmentation should also specify what to do with unbreakable overflow? Maybe css-break should also say something more about it? https://drafts.csswg.org/css-break/#unforced-breaks and https://drafts.csswg.org/css-break/#transforms mention slicing.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/4509 using your GitHub account

Received on Tuesday, 12 November 2019 11:39:59 UTC