css hover对其包含的子元素进行样式设置示例

<ul class="icon-down-single-arr-li">
<li>
<a href="javascript:void(0)">价格<span class="icon-all icon-down-single-arr"></span></a>
</li>
</ul>

.icon-down-single-arr{
background-position: -67px -974px;
}
.icon-down-single-arr-li li:hover .icon-down-single-arr{
background-position: -81px -974px;
}