css二级横向导航代码

<nav class="main-nav">
  <ul>
    <li><a href="#">Home</a></li>
    <li><a href="#">About</a>
      <ul class="sub-menu">
        <li><a href="#">Team</a></li>
        <li><a href="#">History</a></li>
      </ul>
    </li>
    <li><a href="#">Services</a>
      <ul class="sub-menu">
        <li><a href="#">Web Design</a></li>
        <li><a href="#">SEO</a></li>
      </ul>
    </li>
    <li><a href="#">Contact</a></li>
  </ul>
</nav>

/* 基础导航样式 */
.main-nav ul {
  list-style: none;
  padding: 0;
  margin: 0;
  display: flex;
}

.main-nav li {
  position: relative;
}

.main-nav a {
  display: block;
  padding: 10px 20px;
  text-decoration: none;
  color: #333;
}

.main-nav a:hover {
  background-color: #f1f1f1;
}

/* 子菜单样式 */
.sub-menu {
  display: none;
  position: absolute;
  top: 100%;
  left: 0;
  background-color: #fff;
  box-shadow: 0 8px 16px rgba(0,0,0,0.2);
  min-width: 160px;
}

.sub-menu li {
  width: 100%;
}

.sub-menu a {
  padding: 10px 20px;
}

/* 显示子菜单 */
.main-nav li:hover .sub-menu {
  display: block;
}