<div> <ul > <li><span class="aaa">1<span></li> <li><span class="aaa">2<span></li> <li><span class="aaa">3<span></li> <li><span class="aaa">4<span></li></ul><ul> <li><span class="aaa">5<span></li> <li><span class="aaa">6<span></li> <li><span class="aaa">7<span></li> <li><span class="aaa">8<span></li></ul><ul> <li><span class="aaa">9<span></li> <li><span class="aaa">10<span></li> <li><span class="aaa">11<span></li> <li><span class="aaa">12<span></li></ul> </div>*{margin:0;padding:0; box-sizing: border-box;}div{padding:50px;}ul{ height:40px; width:400px;}ul li{ float:left; width:100px; height:40px; line-height:80px; border-bottom:1px solid #ccc; text-align: center; list-style:none; }ul li span{ display:inline-block; width:20px; height:20px;background:red; border-radius:50%; }ul li:first-child{ border-left:1px solid #ccc;}ul:nth-child(2n) li{ float:right}ul:nth-child(2n) li:first-child{ border-right:1px solid #ccc; border-left:none;}ul:first-child li{ border-left:none;}xxxxxxxxxx