[view-transitions-1] Have the -image-pair, -old, and -new pseudos inherit animation-delay

[bramus]

I just caught myself doing this in a project I’m working on:

:root::view-transition-image-pair(*),
:root::view-transition-new(*),
:root::view-transition-old(*) {
  animation-delay: inherit;
}

I needed to do this to sync up the animation-delay from the ::view-transition-group(x) to its child-pseudos.

::root:view-transition-group(header) {
  animation-delay: 1s;
}

Without the first code snippet my animations were not in sync: the default fade-in/fade-out on the new/old pseudo ran at the wrong time.

I was surprised that animation-delay: inherit; on the pseudos isn’t part of the UA stylesheet VT styles, especially since the VT UA styles do exactly that for animation-duration (and animation-fill-mode):

/* UA Stylesheet (selection) */
:root::view-transition-group(*) {
  animation-duration: 0.25s;
}

:root::view-transition-image-pair(*) {
  animation-duration: inherit;
}

:root::view-transition-old(*),
:root::view-transition-new(*) {
  animation-duration: inherit;
}

I think it would be handy to include animation-delay: inherit for the -image-pair, -old, and -new pseudos in the UA stylesheet so that setting a delay on the -group automatically gets applied on the the child pseudos as well, keeping them all in sync.

[astearns]

I see animation-duration: inherit and animation-fill-mode: inherit already defined for these pseudos. Are there any other animation-* properties besides animation-delay that should also inherit here?

[noamr]

I see animation-duration: inherit and animation-fill-mode: inherit already defined for these pseudos. Are there any other animation-* properties besides animation-delay that should also inherit here?

It's clear that -delay needs to be inherited, but the other ones (direction, iteration-count) can go either way. We'd like to resolve on animation-delay only for now.

[astearns]

The CSSWG will automatically accept this resolution one week from now if no objections are raised here. Anyone can add an emoji to this comment to express support. If you do not support this resolution, please add a new comment.

Proposed Resolution: Add animation-delay: inherit to the UA stylesheet rules for (::view-transition) -image-pair, -old, and -new

[astearns]

RESOLVED: Add animation-delay: inherit to the UA stylesheet rules for (::view-transition) -image-pair, -old, and -new