// https://drafts.css-houdini.org/css-typed-om-1/#cssunparsedvalue
[Exposed=(Window, Worker, PaintWorklet, LayoutWorklet)]
interface CSSUnparsedValue : CSSStyleValue {
    constructor(sequence<CSSUnparsedSegment> members);
    iterable<CSSUnparsedSegment>;
    readonly attribute unsigned long length;
    getter CSSUnparsedSegment (unsigned long index);
    setter undefined (unsigned long index, CSSUnparsedSegment val);
};

// https://drafts.css-houdini.org/css-typed-om-1/#typedefdef-cssunparsedsegment
typedef (USVString or CSSVariableReferenceValue) CSSUnparsedSegment;