.modCook {
    float: left;
    width:50%;
    padding-top:20px; 
    margin-left: 10px; 
    height: 90%;
}

.modCook ul.listbox li {
    padding-top: 0;
    padding-bottom: 0;
}
.modCook ul.listbox li.checked {
    /*opacity: .5;*/
    background-color: lightgreen;
}