左右定宽，中间自适应
有几种方法可以实现
改变窗口大小看看？
方案一：
左右设置绝对定位，定宽，中间设置margin-left margin-right
查看 demo
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>左右定宽，中间自适应(1)</title>
<style type="text/css">
*{margin: 0;padding: 0;}
.left{
position: absolute;
top: 0;
left: 0;
width: 200px;
border: 1px solid #333;
background: #aaa;
}
.right{
position: absolute;
top: 0;
right: 0;
width: 220px;
background: #aaa;
}
.middle{
margin-left: 200px;
margin-right: 220px;
border: 1px solid #333;
background: #ccc;
word-break: break-all;
}
</style>
</head>
<body>
<div class="left">
<h4>left</h4>
<p>oooooooooooooo
0000000000000000
00000000000000000
ooooooooooooooo
ooooooooooooooo
000000000000000</p>
</div>
<div class="middle">
<h4>middle</h4>
<p>HHHHHHHHHHHHHHHHHHHHHH
hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
HHHHHHHHHHHHHHHHHHHHHH
hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
</p>
</div>
<div class="right">
<h4>right</h4>
<p>BBBBBBBBBBBBBB
888888888888888888
BBBBBBBBBBBBBBBBBB
88888888888888888888</p>
</div>
</body>
</html>
方案二：
采用负边距处理。左中右都float：left;
中间的div里边再设置一个div ,外层div占满 width:100%; 内层div使用margin-left 和margin-right
左边加上负边距 margin-left:-100% 拉回最左端
右边加上负边距 margin-left:-220px (即为右边的宽度)拉回最右端
查看 demo
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>左右定宽，中间自适应(2)</title>
<style type="text/css">
*{margin: 0;padding: 0;}
.left{
float: left;
margin-left: -100%;
width: 200px;
border: 1px solid #333;
background: #aaa;
}
.right{
float: left;
margin-left: -220px;
width: 220px;
background: #aaa;
}
.middle{
float: left;
width: 100%;
}
.middle-inner{
margin-left: 200px;
margin-right: 220px;
border: 1px solid #333;
background: #ccc;
word-break: break-all;
}
</style>
</head>
<body>
<div class="middle">
<div class="middle-inner">
<h4>middle</h4>
<p>HHHHHHHHHHHHHHHHHHHHHH
hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
HHHHHHHHHHHHHHHHHHHHHH
hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
</p>
</div>
</div>
<div class="left">
<h4>left</h4>
<p>oooooooooooooo
0000000000000000
00000000000000000
ooooooooooooooo
ooooooooooooooo
000000000000000</p>
</div> <div class="right">
<h4>right</h4>
<p>BBBBBBBBBBBBBB
888888888888888888
BBBBBBBBBBBBBBBBBB
88888888888888888888</p>
</div>
</body>
</html>
方案三：
左边使用float:left 右边用float:right，html代码中的中间部分要放后边
查看 demo
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>左右定宽，中间自适应(3)</title>
<style type="text/css">
*{margin: 0;padding: 0;}
.left{
float: left;
width: 200px;
border: 1px solid #333;
background: #aaa;
}
.right{
float: right;
width: 220px;
background: #aaa;
}
.middle{
margin-left: 200px;
margin-right: 220px;
border: 1px solid #333;
background: #ccc;
word-break: break-all;
}
</style>
</head>
<body>
<div class="left">
<h4>left</h4>
<p>oooooooooooooo
0000000000000000
00000000000000000
ooooooooooooooo
ooooooooooooooo
000000000000000</p>
</div>
<div class="right">
<h4>right</h4>
<p>BBBBBBBBBBBBBB
888888888888888888
BBBBBBBBBBBBBBBBBB
88888888888888888888</p>
</div>
<div class="middle">
<h4>middle</h4>
<p>HHHHHHHHHHHHHHHHHHHHHH
hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
HHHHHHHHHHHHHHHHHHHHHH
hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
</p>
</div>
</body>
</html>