[css-view-transitions-1] Naming elements inside shadow DOM via `::part` about csswg-drafts HOT 6 CLOSED

I realize tree-scoping VT comes with a bunch of issues, especially with the pseudo-elements being created only on the root element. Even if you scope VT name to a subtree, that VT name will be exposed to the Document through the pseudo-elements which breaks the scoping.

cc @fantasai

from csswg-drafts.

I realize tree-scoping VT comes with a bunch of issues, especially with the pseudo-elements being created only on the root element. Even if you scope VT name to a subtree, that VT name will be exposed to the Document through the pseudo-elements which breaks the scoping.

What if styling the pseudo-elements (everything under view-transition-group) were also tree-scoped? The only snag would be dealing with :only-child but perhaps we can find a specific solution to that?

from csswg-drafts.

@khushalsagar I'm a bit confused about which part of the spec says that this shouldn't work today. ::part styles are defined in the parent scope, so view-transition-names defined there should apply to the corresponding part inside the shadow DOM.

from csswg-drafts.

I checked and also animation-timeline currently doesn't work on parts. I think there is no reason why this shouldn't work, the encapsulation should be for styles not for elements. cc @flackr

from csswg-drafts.

@khushalsagar I'm a bit confused about which part of the spec says that this shouldn't work today. ::part styles are defined in the parent scope, so view-transition-names defined there should apply to the corresponding part inside the shadow DOM.

It was added here. Though now that you asked maybe "tree context" is not the right term since it's associated with a selector not a node. So the spec text might need to be fixed. But the intent of the resolution was to exclude names from nodes in inner tree scopes.

from csswg-drafts.

Turns out this is not an issue. @andruud clarified that the scoping spec already takes care of ::part by assigning the tree scope to a name based on where the style rule was declared. So using ::part would mean the tree scope of the name is the outer DOM's tree scope.

from csswg-drafts.