td {
      width: 100px;
      height: 100px;
      text-align: center;
      font-size: 48px;
      cursor: pointer;
      border: 1px solid black;
    }

    td:hover {
      background-color: whitesmoke;
    }

    table {
      margin: 0 auto;
      border-collapse: collapse;
    }

    h1 {
      margin-bottom:65px;
      text-align: center;
    }