html{
height: 100%;
overflow-x: hidden;
}
.curtains{
width: 100%;
z-index:1;
position:relative;
}
.curtains>li{
background: white;
display:block;
top: 0;
left: 0;
width: 100%;
min-height: 100%;
overflow: hidden;
z-index:1;
}
.curtains>li.hidden{display:none;}
.curtains>li:first-child{z-index:2;}