ol.abc {    
    list-style-type: none;
    counter-reset:  chapter;    
}

ol.abc li {
    counter-increment: chapter;
    position: relative;
    padding-left: 1.4em;
}

ol.abc li:before {
    position: absolute;
    left: 0;
    top: 0;
    content: counter(chapter, lower-alpha) ') ';
}