nav{
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    /* background:rgba(255,255,255,0.1); */
    background: rgba(0, 0, 0, 0.7);
    z-index: 99;
}
.nav_container{
    width:100%;
    height: 45px;
    color: #fff;
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin:0 auto;
    text-align: center;
}
@media (min-width: 544px){
    .nav_container {
        max-width: 500px;
    } 
}
@media (min-width: 768px){
    .nav_container {
        max-width: 720px;
    } 
    .nav_menu ,.nav_logo{
        display: block;
    }
    .nav_logoimg ,.nav_title, .nav_meanimg{
        display: none;
    }  
    .nav_mainmin{
        display: none;
    }
    .nav_mainmax{
        display: block;
    }
    .nav_menu_hover:after{
        content:"";
        height: 2px;
        width: 80%;
        background: #fff;
        position: absolute;
        bottom:0;
        left:10%;
    }
}
@media (min-width: 992px){
    .nav_container {
        max-width: 940px;
    } 
}
@media (min-width: 1200px){
    .nav_container {
        max-width: 1140px;
    } 
}
@media (max-width: 767px){
    .nav_menu ,.nav_logo{
        display: none;
    } 
    .nav_logoimg ,.nav_title, .nav_meanimg{
        display: block;
    } 
    .nav_mainmin{
        display: block;
    }
    .nav_mainmax{
        display: none;
    }
    .nav_mainmin .nav_menu ul{
        display: block;
        text-align: center;
    } 
}
.nav_logo{
    font-weight: bold;
    font-size: 25px;
    flex: 1;
}
.nav_logoimg{
    width: 50px;
    height: 100%;
    line-height: 35px;
}
.nav_meanimg{
    width: 42px;
    height: 100%;
    line-height: 30px;
}

.nav_menu{
    flex: 2;
}
.nav_menu ul{
    display: flex;
    justify-content: space-around;
    align-items:center;
}
.nav_menu li{
    line-height:45px;
    position: relative;
    cursor: pointer;
    font-size: 14px;
    color:rgba(255,255,255,1);
}
.nav_menu li:hover{
    color: #ccc;
}
.nav_menu_active:after{
    content:"";
    height: 2px;
    width: 80%;
    background: #fff;
    position: absolute;
    bottom:0;
    left:10%;
}