作业：浮动效果
太早2019-07-06 12:07:25183<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>This is a demo</title>
<style>
div{
width: 100%;
overflow: auto;
}
#p1{
width:150px;
height:1000px;
float: left;
background-color: red;
text-align: center;
}
#p2{
background-color: yellow;
height:1000px;
margin-left: 150px;
margin-right: 230px;
text-align: center;
}
#p3{
width:230px;
height: 1000px;
float:right;
background-color: blue;
text-align: center;
}
</style>
</head>
<body>
<div>
<p id="p1">左导航栏</p>
<p id="p3">中间内容</p>
<p id="p2">右导航栏</p>
</div>
</body>
</html>