// https://drafts.csswg.org/scroll-animations-1/#scrolltimeline
[Exposed=Window]
interface ScrollTimeline : AnimationTimeline {
    constructor(optional ScrollTimelineOptions options = {});
    readonly attribute Element? source;
    readonly attribute ScrollAxis axis;
};

// https://drafts.csswg.org/scroll-animations-1/#dictdef-scrolltimelineoptions
dictionary ScrollTimelineOptions {
    Element? source;
    ScrollAxis axis = "block";
};

// https://drafts.csswg.org/scroll-animations-1/#enumdef-scrollaxis
enum ScrollAxis { "block", "inline", "x", "y" };