code: @Nonnull
    @ReturnsMutableCopy
    public ICommonsList <CSSStyleRule> getAllStyleRules ()
    {
      return m_aRules.getAllMapped (r -> r instanceof CSSStyleRule, r -> (CSSStyleRule) r);
    }
docs: Get a list of all top-level rules that are style rules (implementing
  {@link CSSStyleRule}).
  
  @return A copy of all contained style rules. Never <code>null</code>.