src/main/java/com/bazaarvoice/jless/parser/Parser.java
Rule RGB() {
        return FirstOf(
                Sequence(Hex(), Hex(), Hex(), Hex(), Hex(), Hex()),
                Sequence(Hex(), Hex(), Hex())
        );
    }
Rule RGB() {
        return FirstOf(
                Sequence(Hex(), Hex(), Hex(), Hex(), Hex(), Hex()),
                Sequence(Hex(), Hex(), Hex())
        );
    }
Ex: 0099dd / 09d