[css-sizing] Is aspect-ratio affected by box-sizing?

[emilio]

For regular replaced elements it makes sense that the content box is what preserves the ratio:

data:text/html,<img src="http://w3c-test.org/images/blue96x96.png" style="border-width: 10px 40px; border-style: solid; width: 80px; display: block;">

It's less clear to me that's the desired behavior for aspect-ratio. Is it?

[fantasai]

Seems pretty clear in the spec:

auto
Replaced elements with an intrinsic aspect ratio use that aspect ratio; otherwise the box has no preferred aspect ratio. Size calculations involving intrinsic aspect ratio work with the content box dimensions always.
<ratio>
The box’s preferred aspect ratio is the specified ratio of width / height. Size calculations involving preferred aspect ratio work with the dimensions of the box specified by box-sizing.

I guess the exciting thing is what happens with <img width=x height=y>: we want HTML to map into CSS syntax, but the current HTML spec defines the aspect ratio as an "intrinsic aspect ratio"...

[fantasai]

Filed #4951 on the HTML mapping issue. Closing out since afaict the spec is clear. :)

[Loirooriol]

BTW, this was discussed in #4007 (comment)