<!-------------下拉菜单---------------->
<style>
.dropbtn {
   background-color: #4CAF50;
   color: white;
   padding: 16px;
   font-size: 16px;
   border: none;
   cursor: pointer;
}

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

.dropdown-content {
   display: none;
   position: absolute;
   background-color: #f9f9f9;
   min-width: 160px;
   box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
}

.dropdown-content a {
   color: black;
   padding: 12px 16px;
   text-decoration: none;
   display: block;
}

.dropdown-content a:hover {background-color: #f1f1f1}

.dropdown:hover .dropdown-content {
   display: block;
}

.dropdown:hover .dropbtn {
   background-color: #3e8e41;
}
</style>
<!-------------下拉菜单---------------->

<div class="dropdown">
 <button class="dropbtn">下拉菜单</button>
 <div class="dropdown-content">
   <a href="AAA">AAA</a>
   <a href="BBB">BBB</a>
   <a href="CCC">CCC</a>
 </div>
</div>