.nav_box{
    
}
.topTiaoFu{
    width: 100%;
    height: 90px;
    position: relative;

    -webkit-transition: 0.3s;
    -moz-transition: 0.3s;
    -ms-transition: 0.3s;
    -o-transition:0.3s;
    transition: 0.3s;

display: none;
}
.topTiaoFu img{
    display: block;
    position: absolute;
    top: 0;
    left: 50%;
    margin-left: -960px;
}
.topTiaoFuAct{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 90px;
    z-index: 9999999;

    -webkit-transition: 0.3s;
    -moz-transition: 0.3s;
    -ms-transition: 0.3s;
    -o-transition:0.3s;
    transition: 0.3s;
}