.board td {
  width: 55px;
  height: 55px;  
  font-size: 35px;
  text-align: center;
  background: #f0d9b5;
  margin: 0;
  padding: 0;
  border: 0;
}

.board td.highlight, .board td.highlightable:hover {
  border: 4px solid #fff;
}

table, tr, td {
  border-spacing: 0;
  border-collapse: collapse;
  box-sizing: border-box;
}

.board tr:nth-child(even) td:nth-child(odd), .board tr:nth-child(odd) td:nth-child(even) {
  background: #b58863;
}