Re: [csswg-drafts] [filter-effects] `drop-shadow()` combined with `transform` has interop issues (#12546)

> > At least there's a [list of grouping property values in CSS Transforms](https://drafts.csswg.org/css-transforms-2/#grouping-property-values) including `filter` that suppress 3d transformations.
> > Maybe that same list of properties should apply in this case as well for consistency?
> 
> I don't see why or how this list would apply here, since the transform in this case isn't a 3D one and most of the other properties in that list have very little to do with when filters need to render.
> 
> Are you suggesting the properties on there should suppress non-3D transforms as well? If so, that seems very backwards-incompatible and highly unintuitive to authors.

My statement that they suppress 3d transformations was actually incorrect. They only require the UA to flatten their representation before any transformations are applied.
And you're right, that list of properties is unrelated. Sorry that I mixed this up!

Btw. Safari agrees with Chrome, i.e. the drop shadow is mirrored by the transform.

And I come to think that this is the correct behavior, because transforms generally affect the filters. So, e.g. if you have `transform: scaleX(-2);` the width of the shadow is 20px in all three engines.
Therefore it looks like a bug in Firefox.

My initial question stays, though. What's applied first? I couldn't find a clear note about that or, generally speaking, at which state of the rendering process transforms are actually applied.

> Having said that, there might be use cases in which users might control the order in which they are applied.

With the previous realizings in mind, that's still valid. Though it's worth to be discussed in a separate issue, I guess.

Sebastian

-- 
GitHub Notification of comment by SebastianZ
Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/12546#issuecomment-3146794894 using your GitHub account


-- 
Sent via github-notify-ml as configured in https://github.com/w3c/github-notify-ml-config

Received on Saturday, 2 August 2025 22:27:36 UTC