body{
    display: flex;
  }
  
  .chessboard {
    width: 640px;
    height: 640px;
    border: 25px solid #333;
    transform: scale(0.75);
  }
  .box {
    display: flex;
    align-items: center;
    justify-content: center;
    float: left;
    width: 80px;
    height: 80px;
    font-size: 4rem;
    text-align:center;
    display: table-cell;
    vertical-align:middle;
  }
  
  .black{
    background-color: #999;
    opacity: 0.8;
  }

  img{
    position: fixed;
    width: 60px;
    height: 60px;
    margin-top:8px;
  }

  #fondo {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: black;
    z-index: 99;
    display: none;
}
#casillas{
  color: white;
  font-size: 5rem;
  z-index: 100;
}