[csswg-drafts] [css-overflow-5] overflow-clip-margin: content-box should not apply border radius to the content box. (#13388)

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

== [css-overflow-5] overflow-clip-margin: content-box should not apply border radius to the content box. ==
The [overflow-clip-margin property specified in css-overflow](https://drafts.csswg.org/css-overflow/#overflow-clip-margin) supports a content-box value. I'm not sure where it is specified, but in building a [demo](https://jsbin.com/hiyizoj/edit?html,css,output) I found it to have unexpected behavior.

In particular, this is my setup. The element has `border-radius: 50%` and some left and top padding resulting in the content-area filled by the only child with a pale yellow background:

<img width="409" height="411" alt="Image" src="https://github.com/user-attachments/assets/c8b6ec4f-0253-4f43-abcb-08e3eee3d7c1" />

When we apply `overflow: clip; overflow-clip-margin: content-box` to the container however, the border radius is applied to the clipping content-box:

<img width="409" height="411" alt="Image" src="https://github.com/user-attachments/assets/56898b56-47da-4ae2-a7d5-14841a8c2b4d" />

I would have expected it to clip to the content box with the corners slightly clipped due to intruding border, i.e.

<img width="409" height="411" alt="Image" src="https://github.com/user-attachments/assets/94c0ccf4-8fe2-4691-86e4-5a314c31d3e3" />

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/13388 using your GitHub account


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Received on Friday, 23 January 2026 15:57:59 UTC