Create a subtle “recessed” looking divider line. The example restyles the tag but it can applied to anything.
hr {
margin: 17px 0 18px;
height: 0;
clear: both;
border: solid #ddd;
border-width: 1px 0 0;
border-top: 1px solid #ddd;
border-bottom: 1px solid #fff;
}