使用CSS悬停创建最简单的下拉菜单

<ul class="dropdown-menu">
  <li><a href="#">菜单项1</a></li>
  <li><a href="#">菜单项2</a></li>
  <li><a href="#">菜单项3</a></li>
</ul>

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

.dropdown-menu li {
  display: none;
}

.dropdown-menu:hover li {
  display: block;
}

.dropdown-menu {
  position: relative;
  display: inline-block;
  background-color: #f9f9f9;
  border: 1px solid #ccc;
  padding: 10px;
}

.dropdown-menu li {
  display: none;
}

.dropdown-menu:hover li {
  display: block;
}

.dropdown-menu li a {
  color: #333;
  text-decoration: none;
}

.dropdown-menu li a:hover {
  background-color: #ddd;
}