#app, #app div {
    display: flex; 
    height: 100%; 
    width: 100%;
  }
  
  #app img {
    width: 100%;
    height: auto;
    z-index: 0;
    align-self: center;
  }
  
  #app video {
    height: 100vh;
    margin: 0 auto;
    display: block;
  }
  
  #app .floatBtn {
    display: block;
    width: 40px;
    height: 32px;
    border-radius: 50%;
    background-color: rgba(0,0,0,.3);
    color: white;
    z-index: 10;
    position: absolute;
    top: 50vh;
    text-align: center;
    padding-top: 8px;
  }
  
  #app .floatBtn.left {
    left: 10px;
  }
  
  #app .floatBtn.right {
    right: 10px;
  }
  
  #app .floatBtn.bottom {
    left: 49%;
    top: 90%;
  }
  
  #app .empty {
    text-align: center;
    margin-top: 48vh;
  }