pub(crate) trait CSSGroupingRuleMethods<D>where
    D: DomTypes,{
    // Required methods
    fn CssRules(
        &self,
        _can_gc: CanGc,
    ) -> Root<Dom<<D as DomTypes>::CSSRuleList>>;
    fn InsertRule(
        &self,
        rule: DOMString,
        index: u32,
        _can_gc: CanGc,
    ) -> Result<u32, Error>;
    fn DeleteRule(&self, index: u32, _can_gc: CanGc) -> Result<(), Error>;
}