== should format at rule position-fallback ==
@position-fallback --button-popover {
  @try {
    top: anchor(--button bottom);
    left: anchor(--button left);
  }

  @try {
    bottom: anchor(--button top);
    left: anchor(--button left);
  }
}

[expect]
@position-fallback --button-popover {
    @try {
        top: anchor(--button bottom);
        left: anchor(--button left);
    }

    @try {
        bottom: anchor(--button top);
        left: anchor(--button left);
    }
}