[css-display] Can run-in be inserted as child of block which establishes an inline formatting context?

[Loirooriol]

CSS Display defines Run-In Layout as

A run-in box behaves exactly as an inline-level box, except:

• If a run-in sequence is immediately followed by a block box that does not establish a new formatting context, it is inserted as direct children of the block box [...]
• Otherwise, an anonymous block box is generated around the run-in sequence and all immediately following inline-level content (up to, but not including, the next run-in sequence, if any).
• A run-in box with a flow inner display type inlinifies its contents.

The following example is provided:

<dl class='dict'>
  <dt>dictionary
  <dd>a book that lists the words of a language in alphabetical
      order and gives their meaning, or that gives the equivalent
      words in a different language.
  <dt>glossary
  <dd>an alphabetical list of terms or words found in or relating
      to a specific subject, text, or dialect, with explanations; a
      brief dictionary.
</dl>

.dict > dt {
  display: run-in;
}
.dict > dt::after {
  content: ": "
}

Which is formatted as:

dictionary: a book that lists the words of a language
in alphabetical order and explains their meaning.

glossary: an alphabetical list of terms or words found
in or relating to a specific subject, text, or dialect,
with explanations; a brief dictionary.

However, the dd establishes an inline formatting context according to CSS 2.1:

A block container box either contains only block-level boxes or establishes an inline formatting context and thus contains only inline-level boxes.

So I think that either the example is wrong and the dt should not be inserted inside the dd, or that the definition should allow a run-in sequence to be inserted as direct children of a block box which establishes an inline formatting context.

[fantasai]

The latter is clearly the only reasonable interpretation. :) This is going to require some tricky wording fixes, though. :/

[Loirooriol]

What about adding the word "block"?

If a run-in sequence is immediately followed by a block box that does not establish a new block formatting context [...]

[fantasai]

There's also flex and grid formatting contexts... so really we need to exclude inline. :)

[fantasai]

But there's related wording that probably also needs fixup, so we need to audit all of it.

[Loirooriol]

As far as I know the only formatting contexts that can be established by a block box are block and inline ones, so flex and grid ones are already excluded.

[fantasai]

Oh, yeah. :) That would definitely work then.

[fantasai]

All fixed, thank you!