css last child

li:last-child {
    background-color: lime;
}/*This will only work if the last child of someEID has 
the class .myclassName 
if the last child does not have class name us js*/
#someEID .myClassName:last-child {
    background: blue;
}
 var x = document.getElementById("myList").lastElementChild.innerHTML; p:last-child {
  font-size: 0.75em;
}