仅使用css向下滑动下拉菜单

<div class="dropdown">
  <button class="dropbtn">菜单</button>
  <div class="dropdown-content">
    <a href="#">选项1</a>
    <a href="#">选项2</a>
    <a href="#">选项3</a>
  </div>
</div>

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

.dropbtn {
  background-color: #f1f1f1;
  color: #333;
  padding: 10px;
  border: none;
  cursor: pointer;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
}

.dropdown-content a {
  color: #333;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}

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