body {
  display: flex;
  flex-direction: column;
  align-items: center;
  font-family: sans-serif;
  background-color: #222; /* 深色背景 */
  color: #fff;
}

#game {
  display: grid;
  grid-template-columns: repeat(8, 60px);
  grid-template-rows: repeat(8, 60px);
  border: 2px solid #fff;
  margin-top: 20px;
}

.square {
  width: 60px;
  height: 60px;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 36px;
  cursor: pointer;
}

.white {
  background-color: #eee;
  color: #000;
}

.black {
  background-color: #666;
  color: #fff;
}

.selected {
  outline: 3px solid red;
}

.highlight {
  outline: 3px solid green;
}