ol.letters li { 
    list-style: none;
}
ol.letters li::before { 
    counter-increment:list1;
    content: "(" counter(list1, lower-alpha) ")"; 
    counter-reset: list2;
}

ol.numbers li {
    list-style: none;
}

ol.numbers li::before {
    counter-increment:list2;
    content: "(" counter(list2, decimal) ")"; 
    counter-reset: list3;
}

ol.innerletters li { 
    list-style: none;
}

ol.innerletters li::before { 
    counter-increment: list3;
    content: "(" counter(list3, lower-alpha) ")"; 
    counter-reset: list4;
}