当鼠标悬停在名称上时更改下拉箭头的颜色

<div class="dropdown">
  <span class="dropdown-text">名称</span>
  <span class="dropdown-arrow"></span>
</div>

.dropdown {
  position: relative;
  display: inline-block;
}

.dropdown-text {
  padding: 10px;
  background-color: #f1f1f1;
  cursor: pointer;
}

.dropdown-arrow {
  position: absolute;
  top: 50%;
  right: 10px;
  transform: translateY(-50%);
  width: 0;
  height: 0;
  border-style: solid;
  border-width: 5px 5px 0 5px;
  border-color: #888 transparent transparent transparent;
}

.dropdown:hover .dropdown-arrow {
  border-color: #ff0000 transparent transparent transparent;
}