.page_nav{
        width: 100%;
        line-height: 50px;
        background: #fff;
        position: fixed;
        height: 50px;
        top: 0;
        display: none;
        z-index: 22;
        left: 0;
        /* transition: all 250ms; */
        box-shadow: 0px 1px 5px #ccc;
        border-bottom: 1px solid #ccc;
    }
    .page_nav_con{
        width: 1440px;
        margin: 0 auto;
    }

    .big_title a{
        font-size: 14px;
        color: #3b3e40;
        font-weight: 400;
        text-decoration: none;
        display: block;
        float: left;
        margin-left: 15px;
    }
    .big_title span{
        display: block;
        float: left;
        height: 56px;
        margin-top: 15px;
        width: 23px;
        background: url(https://img-en.fs.com/zh/includes/templates/fiberstore/images/menu_xg.png) no-repeat center 7px;
    }
    .short_title{
        float: right;
    }
    .short_title a{
        padding: 0 18px;
        text-decoration: none;
        color: #3b3e40;
        font-size: 14px;
        border-right: 1px solid #dedede;
    }
    .short_title a:hover{
        color: #2971ba;
        text-decoration: none;
    }
    .big_title a:hover{
        color: #2971ba;
        text-decoration: none;
    }