css网页布局下拉框架

<nav>
  <ul>
    <li><a href="#">首页</a></li>
    <li><a href="#">服务</a></li>
    <li class="dropdown">
      <a href="#" class="dropbtn">更多</a>
      <div class="dropdown-content">
        <a href="#">服务1</a>
        <a href="#">服务2</a>
        <a href="#">服务3</a>
      </div>
    </li>
  </ul>
</nav>

nav ul {
  list-style-type: none;
  padding: 0;
  margin: 0;
}

nav li {
  float: left;
}

nav a {
  display: block;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

.dropdown {
  position: relative;
}

.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: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
}

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

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