Builder pattern with inheritance and multiple generics

I try to figure out the best approach for writing Builder with N generics and inheritance and it seems not so straightforward, probably it's incorrect approach from design perspective but I would be glad to get any suggestion in this situation.

I have a parent class:

public class Base<F extends Element, C extends Rule> {

    public Base(Builder<F, C> builder) {}

    protected abstract class Builder<F1 extends Element, C1 extends Rule> {
        private Class<F1> focusClass = (Class<F1>) Dot.class;
        private Class<C1> ruleClass = (Class<C1>) ComplicatedRule.class;

        protected Builder() {
        }

        public Builder<F1, C1> focusClass(Class<F1> focusClass) {
            this.focusClass = focusClass;
            return this;
        }
    }
}

And one of the child classes:

public class ChildA<S extends Element, F extends Element, C extends Rule> extends Base<F, C> {
    private ChildA(Builder<S, F, C> builder) {
        super(builder);
    }

    public class Builder<S1 extends Element, F1 extends Element, C1 extends Rule>
            extends Base<F1, C1>.Builder<F1, C1> {
        private Class<S1> searchClass = (Class<S1>) Line.class;

         public Builder() {
            super();
        }

        public Builder<S1, F1, C1> searchClass(Class<S1> searchClass) {
            this.searchClass = searchTClass;
            return this;
        }

        public ChildA build() {
            return new ChildA<>(this);
        }
    }
}

It fails with compilation error in ChildA. Does it exist any way to make it less terrifying and simpler?