如何将滚动添加到下拉菜单？

<select class="custom-select" size="5">
  <option value="1">菜单项 1</option>
  <option value="2">菜单项 2</option>
  <option value="3">菜单项 3</option>
  <option value="4">菜单项 4</option>
  <option value="5">菜单项 5</option>
  <option value="6">菜单项 6</option>
  <option value="7">菜单项 7</option>
  <option value="8">菜单项 8</option>
  <option value="9">菜单项 9</option>
  <option value="10">菜单项 10</option>
</select>

.custom-select {
  width: 200px;
  height: 100px;
  overflow: scroll;
}

/* 可选：自定义滚动条样式 */
.custom-select::-webkit-scrollbar {
  width: 8px;
}

.custom-select::-webkit-scrollbar-thumb {
  background-color: #888;
  border-radius: 4px;
}

.custom-select::-webkit-scrollbar-track {
  background-color: #f1f1f1;
}