<ul> <li><a href='#'>first-child</a></li> <li><a href='#'>nth-child(2)</a></li> <li><a href='#'>nth-child(3)</a></li> </ul>
li a{color:#fff;}
li:first-child a{ background:#333; } /* :first-child is supported */
li:first-child + li a{background:#666; } /* :nth-child(2) */
li:first-child + li + li a{background:#999; } /* :nth-child(3) */