* {margin:0;padding:0;}

body {
 font-family: arial, 宋体, serif;
        font-size:12px;
}

#nav {
  height: 24px;  list-style-type: none;  padding-left:78px;

line-height:24px;overflow:hidden;background:#647881;
}

#nav a {
 display: block; width: 78px; text-align:center;}

#nav a:link  {
 color:#FFFFFF; text-decoration:none;
}
#nav a:visited  {
 color:#fff;text-decoration:none;
}
#nav a:hover  {
 color:#FFF;text-decoration:none;font-weight:bold;background:#ccc;
}

#nav li {
 float: left; width: 78px;
}


#nav li ul {
 line-height: 24px; 
 list-style-type: none;
 text-align:content;
 left: -999px;
 width: 550px; //注意,这里一定要设置宽度;
 position: absolute;
 background:#2591ce;
}

#nav li ul li{
  float: content;width: 78px; //float就是子菜单横向的关键,可以继承父菜单而省略float
}


#nav li ul a{
 display: block; width:80px;text-align:content;
}

#nav li ul a:link  {
 color:#FFFFFF; text-decoration:none;
}
#nav li ul a:visited  {
 color:#ffffff;text-decoration:none;
}
#nav li ul a:hover  {
 color:#FFF;text-decoration:none;
}

#nav li:hover ul {
 left:25%;
}

#nav li.sfhover ul {
 left:25%;
}

#content {
 clear: content;
}