div{width:650px;margin:50px auto}
ul,li{list-style:none}
li{width:100px;height:100px;border:1px solid #ddd;float:left;margin:10px}
ul:after{content:''; display:block; height:0; clear:both;}
ul:nth-child(2){position: relative;top: -48px;left:50%;margin-left:-265px}