css 设置下拉菜单

html

<li class="nav-li active">
<a href="javascript:void(0)">部门概况</a>
<div class="dropDown">
<a target="_blank" href="/SWJTUXG/Website/Home/InfoShow?LJw34Jmu=010101.shtml">部门简介</a>
<a target="_blank" href="/SWJTUXG/Website/Home/InstitutionSetting">工作人员</a>
</div>
</li>

　

css

nav-li .dropDown { 

transition: all 0.5s ease-in-out;
visibility: hidden;
opacity: 0;
}
 

.nav .nav-box .nav-li:hover .dropDown {
visibility: visible;
opacity: 1;
}