There are a few ways, but working with your code...
ul li, ul.menu li, ul.links li, .item-list ul li {
background: url("images/marker.png") no-repeat scroll 4px center rgba(0, 0, 0, 0);
list-style: square inside;
margin: 0 0 0 15px;
padding: 0 0 0 15px;
}
Seems to do the trick and give the lists/bullets a more natural appearance.