.nTab{
        float: left;
        width: 280px;
        margin: 0 auto;
        border-bottom:1px #AACCEE solid;
        background:#d5d5d5;
        background-position:left;
        background-repeat:repeat-y;
        margin-bottom:2px;
      }

总体宽度

 .nTab .TabTitle li{
        float: left;
        width: 70px;
        cursor: pointer;
        padding-top: 4px;
        padding-right: 0px;
        padding-left: 0px;
        padding-bottom: 2px;
        list-style-type: none;
      }

单个选项卡宽度