纯css二级导航下拉菜单
*{margin: 0;padding: 0;}
#bg{background: red;width: 100%;height: 35px;}
nav{height: 35px;width: 1000px;margin: 0 auto;}
nav ul li{list-style-type:none;float: left}
nav ul li a{ text-decoration: none;display: block;width: 130px;line-height: 35px;
text-align: center;color:white;font-fimily:微软雅黑;}
nav ul li ul li{float: none}
nav ul li ul li a{color:black}
nav ul li ul{display: none;}
nav ul li:hover ul{display: block;}
