[csswg-drafts] [css-sizing] Statements on calculating used sizes and positions of a containing block in percentage-sized cyclic dependency is ambiguous

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

== [css-sizing] Statements on calculating used sizes and positions of a containing block in percentage-sized cyclic dependency is ambiguous ==
The following statements in [the spec](https://drafts.csswg.org/css-sizing-3/) seem ambiguous to me:

> If the cyclic dependency was introduced **due to** a block-size or max-block-size on the containing block that causes it to depend on the size of its contents, the box’s percentage is not resolved and instead behaves as auto.

Here the "due to" can be interpreted as either _a sufficient condition_, or _a necessary condition_, or _a sufficient and necessary condition_. For example, it's ambiguous as to whether the following code is considered to satisfy the condition:

```
<article style="height: auto; min-height: min-content;">
  <aside style="height: 50%;">
    ...
  </aside>
</article>
```

If the "due to" is interpreted as a sufficient condition, then the code satisfies the condition; if the "due to" is interpreted as the other two meanings, it doesn't, because `height: auto;` is not necessary for cyclic dependency to be introduced in this example, `min-height` can also cause cyclic dependency.

Although the second code snippet in Example 7 on that page implictly removes the ambiguity(I.e. it implictly shows the "due to" means a sufficient condition); but the statements are ambiguous on its own.

So I suggest rephrasing the statements quoted above to something like this:

> If a block-size or a max-block-size on the containing block (despite all other size properties) was just sufficient to introduce the cyclic dependency, the box’s percentage is not resolved and instead behaves as auto.

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/2953 using your GitHub account

Received on Thursday, 26 July 2018 14:26:27 UTC