<style> .container{ float:left; position:relative; left:50%} .container ul{ ... position:relative; left:-50%;} .container li{ float:left;display:inline; ...} </style>
<body> <div class="container"> <ul> <li>...</li> </ul> </div> </body>
父元素.container已经设置了left: 50%,为什么子元素ul,li设置left: -50%还要加上父元素.container?
Caballarii