body{
  background: #007439;
}
#game{
  width: 400px;
  height: 800px;
  border: 4px solid #FF9473;
  border-top: 0;
  position: absolute;
  top: 0px;
  bottom: 0px;
  left: 0px;
  right: 0px;
  margin: auto;
  line-height: 0;
}
  #game .cell{
    width: 30px;
    height: 30px;
    display: inline-block;
    margin: 5px;
  }
    #game .cell.visible{
      background: #FF9473;
    }