[scroll-animations-1][css-animations-2] Out-of-range range offsets #8578
Description
Currently animation-range-start/end take <length-percentage> values to indicate a position on the timeline. By allowing <length> values in #7575, we made it possible to choose positions outside the declared range; and unless we restrict the percentages to [0%,100%], that can be done with percentages also.
The question here is, what do we do about such out-of-range values?
- Make negative values and percentages outside [0%,100%] invalid, and clamp any other values to the named range.
- Allow all values as syntactically valid, but clamp them to the named range.
- Make negative values and percentages outside [0%,100%] invalid when a range name is not specified, and clamp all values to the timeline.
- Allow all values as syntactically valid, but clamp them to the timeline.
- Allow all values, and allow
animation-rangeto expand the attachment range for animations.
I think the last one makes the most sense. See also #8405 (comment)