css实现导航菜单下拉效果

<style>
    *{padding: 0;margin: 0;}  /* 先重置一下html，消除HTML标签默认的内外边距 */
    .wrap{width: 800px;margin: 0 auto;}    /* 对导航的内容设置一个主体为800px的宽并使其居中 */
    .clear{clear: both;}  /* 清除浮动 */
    a{text-decoration-line: none;}   /* 去掉默认a标签的下划线 */
    ul,li{list-style: none;}
    nav .level>li{float: left;width: 16.66%;text-align: center;background: bisque;padding: 10px 0;font-size: 16px;}
    nav .level>li a{color: black;}
    nav .level>li:hover{background: red;}   /* 设置鼠标滑过后的样式 */
 
    nav .two{display: none;}  /* 先使二级菜单的内容隐藏 */
    nav .level>li:hover .two{display: block;}   /* 鼠标滑过一级菜单后的显示二级菜单 */
</style>
<nav>
        <ul class="level">
            <li><a href="">首页</a></li>
            <li>
                <a href="">栏目1</a>
                <ul class="two">
                    <li>二级菜单1</li>
                    <li>二级菜单2</li>
                    <li>二级菜单3</li>
                </ul>
            </li>
            <li>
                <a href="">栏目2</a>
                <ul class="two">
                    <li>二级菜单4</li>
                    <li>二级菜单5</li>
                    <li>二级菜单6</li>
                </ul>
            </li>
            <li>
                <a href="">栏目3</a>
                <ul class="two">
                    <li>二级菜单7</li>
                    <li>二级菜单8</li>
                    <li>二级菜单9</li>
                </ul>
            </li>
            <li>
                <a href="">栏目4</a>
                <ul class="two">
                    <li>二级菜单10</li>
                    <li>二级菜单11</li>
                    <li>二级菜单12</li>
                </ul>
            </li>
            <li>
                <a href="">栏目5</a>
                <ul class="two">
                    <li>二级菜单13</li>
                    <li>二级菜单14</li>
                    <li>二级菜单15</li>
                </ul>
            </li>
        </ul>
    </nav>