#bkbox{position:fixed;left:0;top:0;width:100%;height:100%;background:#000;color:#fff;z-index:9999;}
#bkbox span{display:block;}
#bkbox .ob {
    position: fixed;
    left: 0;
    right: 0;
    top: 0;
    bottom: 60px;
    display: flex;
    flex-direction: column;
    align-items: stretch;
}

#bkbox .im{background-repeat:no-repeat;background-position:center center;/*background-size:contain;height:100%;*/}
#bkbox .tx{text-align:center;}
#bkbox i{margin-left:-100px;position:fixed;bottom:0;left:50%;display:block;float:left;width:60px;height:60px;background-image:url('/bkbox/bkbox.png');cursor:pointer;}
#bkbox .x{margin-left:-30px;background-position:-118px 0;}
#bkbox .n{margin-left:40px;background-position:-59px 0;}
#bkbox .im2{
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%,-50%);
  max-width: 100%;
  max-height: 100%; 
}
#bkbox .ob2 { flex-grow: 1;position: relative; }