.slider{
    width:100%;
    height:80vh;
    background-color:#CCC;
    position:relative;
    overflow:hidden;
    background-position:center center;
    background-repeat:no-repeat;
    background-size:cover;
}

.video_youtube{
    border:1px solid red;
    position:absolute;
    left: -52px;
    right: -72px;
    top: -39px;
    bottom: -49px;
    z-index:1;
}

.bg_fon_video{
    position:absolute;
    height:100%;
    width:100%;
    overflow:hidden;
    z-index:2;
}

@media only screen and (max-width: 1200px){ 
    .slider{
        width: 100%;
        height: 40vw;
    }
}

@media only screen and (max-width: 768px){  
    .slider{
        width:100%;
        height:50vh;
    }
    
    .video_youtube{
        display:none;
    }
    
    .bg_fon_video{
        background-position:center center;
        background-repeat: no-repeat;
        background-size:cover;
        background-image:url(../img/vfon2.JPG);
    }
}