[scroll-animations-1] Define keyframe attachment outside animation's effective range #7825

Author: fantasai

scroll-animations-1/Overview.bs

@@ -731,6 +731,11 @@ spec: cssom-view-1; type: dfn;
 	If the timeline does not have a corresponding [=named timeline range=],
 	then any keyframes attached to points on that [=named timeline range=]
 	are ignored.
+	It is possible that these attachment points
+	are outside the [=active phase=] of the animation;
+	in these cases the automatic ''from'' (0%) and ''to'' (100%) keyframes
+	are only generated for properties that don't have keyframes
+	at or earlier than 0% or at or after 100% (respectively).
 
 ## Attaching Animations to Timeline Ranges ## {#named-range-animation-declaration}