.box {
      width: 100px;
      height: 100px;
      background-color: lightblue;
      border: 2px solid blue;
      text-align: center;
      font-size: 24px;
      line-height: 100px;
      margin: 5px;
      cursor: pointer
      }

#startButton {
  margin-top: 10px;
}