body, html{
    width: 100%;
    height: 100vh;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
}


#container{
    width: 70%;
    height: 80%;
    display: flex;
    justify-content: center;
    align-items: center;
    position: relative;
     z-index: 1;
}

img,video{
    display: none;
    position: absolute;
    height: 80%
}


#bck{
    display: block;
    position: fixed;
    right: 0;
    bottom: 0;
    min-width: 100vw; 
    min-height: 120%;
    z-index: 0;
}