.bg{
position:absolute;
width:100%;
height:100%;
top:0px;
left:0px;
background-image:url(bg-cleanday.png);
background-size:cover;
background-position:center bottom;

}
audio{
opacity:0;
}
.play_box{
position:absolute;
width:100%;
height:100%;
top:0px;
left:0px;
background-color:rgba(0,0,0,.85);
background-size:cover;
background-position:center bottom;
cursor: pointer;

}
.btn{
position:absolute;
width:80px;
height:80px;
top:50%;
left:50%;
transform: translateX(-50%) translateY(-50%) scale(1.3);
background-image:url(play.png);
background-size:cover;
background-position:center top;
}