[csswg-drafts] Flexbox stretch issue: aspect-ratio width ignored compared to explicit width (#13937)

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

== Flexbox stretch issue: aspect-ratio width ignored compared to explicit width ==
**Summary:**
Flexbox `stretch` behavior appears to ignore width derived from `aspect-ratio`,  
while explicit `width`/`min-width`/`max-width` values `prevent` stretching.  
In effect, `stretch` seems to treat aspect-ratio sizing as if the width were `auto`,  
rather than respecting the intrinsic width implied by the ratio.

This creates an inconsistency where `aspect-ratio` does not `behave` like
other intrinsic sizing constraints in the cross axis.

**Reproduction:**

```html
<div class="wrapper">
  <button>Button</button>
</div>
```

```css
.wrapper {
  display: flex;
  flex-direction: column;
}

button {
  height: 48px;
  aspect-ratio: 1;
}
```

**Current behavior:**
The button stretches to fill the entire width of the flex container.

**Expected behavior:**
Since aspect-ratio combined with a definite height produces a predictable width,
it may be expected to behave similarly to explicit width sizing and prevent stretch behavior.

**Workaround:**
```css
align-items: flex-start;
```

or

```css
width: fit-content;
```



**Question:**
Is this intentional Flexbox behavior,
a specification limitation,
or an implementation detail inherited from pre-aspect-ratio sizing rules?

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13937 using your GitHub account


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Received on Sunday, 17 May 2026 20:41:19 UTC