.trailing-non-name-start {
  // We want to treat interpolation as though it's a valid identifier character,
  // which means that if it's followed by a [name character][] that's not a
  // [name start character][] it should still treat that as part of the
  // identifier.
  //
  // [name character]: https://drafts.csswg.org/css-syntax-3/#name-code-point
  // [name start character]: https://drafts.csswg.org/css-syntax-3/#name-start-code-point
  digit: foo#{bar}12;
  hyphen: foo#{bar}-12;
  double-hyphen: foo#{bar}--12;
}