利用浮动和定位实现导航条效果
<!DOCTYPE html>
<html>
<head>
<title>导航条</title>
<meta charset="utf-8">
<link rel="shortcut icon" type="image/x-icon" href=""><!-- 图标 -->
<link rel="stylesheet" type="text/css" href=""><!-- 可以引入外部css文件 -->
<style type="text/css">
.clear{ clear: both; }/*清除浮动left、right、both*/
ul li{
list-style: none;/*去掉li前面的标记*/
width: 100px;
height: 40px;
line-height: 40px;/*行高，不允许用负值*/
background-color: #ccc;
text-align: center;
margin: 0px 1px;
float: left;/*左浮动*/
position: relative;/*相对定位*/
}
ul li:hover{background: red;color: blue;}
ul li ul{
width: 100px;
height: 100px;
position: absolute;/*绝对定位*/
left: -41px;
display: none;
}
ul li:hover .meau{/*竟然还有自动识别功能*/
display: block;
}
.box1{
width: 200px;
height: 200px;
background-color: #ff2;
float: right;
}
</style>
</head>
<body>
<ul>
<li>HTML
<ul class="meau"><!-- 只有一个class名，移动到这个li上面其他两个(css和js)竟然没有都显示出来 -->
<li>HTML1</li>
<li>HTML2</li>
<li>HTML3</li>
</ul>
</li>
<li>CSS
<ul class="meau">
<li>CSS1</li>
<li>CSS2</li>
<li>CSS3</li>
</ul>
</li>
<li>JavaScript
<ul class="meau">
<li>JavaScript1</li>
<li>JavaScript2</li>
<li>JavaScript3</li>
</ul>
</li>
<li>MySQL</li>
<li>PHP</li>
</ul>
<div class="clear"></div>
<div class="box1">div1</div>
<div class="box1">div2</div>
<div class="box1">div3</div>
</body>
</html>