如何使用材质角度显示/隐藏下拉列表

<select id="myDropdown">
  <option value="option1">Option 1</option>
  <option value="option2">Option 2</option>
  <option value="option3">Option 3</option>
</select>

#myDropdown {
  width: 200px;
  background-color: #f2f2f2;
  color: #333;
}

var dropdown = document.getElementById("myDropdown");

dropdown.addEventListener("click", function() {
  if (dropdown.classList.contains("show")) {
    dropdown.classList.remove("show");
  } else {
    dropdown.classList.add("show");
  }
});

#myDropdown {
  /* 初始状态 */
  transform: rotateX(-90deg);
  opacity: 0;
  transition: transform 0.3s, opacity 0.3s;
}

#myDropdown.show {
  /* 显示状态 */
  transform: rotateX(0);
  opacity: 1;
}