Adds subtle (or not so subtle, depending on the background) border to list items.

Borderlands

li {
    border-top: 1px solid rgba(255,255,255,0.1);
    border-bottom: 1px solid rgba(0,0,0,0.2);
  }

li:first-child {
     border-top: none;
     }

li:last-child {
     border-bottom: none;
     }