.wraper{ width:800px; padding-top:5px; margin:0 auto}
.nav{ position:relative; width:800px; height:40px;  overflow:hidden}
.nav-item{ position:relative; float:left; width:105px; height:40px; line-height:40px; text-align:center; font-size:14px; z-index:1}
.nav-item a{ display:block; height:40px; color:#000000; font-size:14px;}
.nav-item a:hover{ color:#F00;}
.move-bg{ display:none;position:absolute;left:0;top:0; width:105px; height:40px; background:#b91919; z-index:0}