<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>经典三列布局，两侧定宽，中间自适应</title>
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
<style>
/* 方式一 */
/*将对象作为弹性伸缩盒显示*/
.all{
display: flex;
}
.div1{width: 200px;background-color: #f00;height:300px;font-size:20px}
.div2{flex:1;background-color: #0f0;height:300px;font-size:20px}
.div3{width: 200px;background-color: #00f;height:300px;font-size:20px}
</style>
</head>
<body>
<div class="all">
<div class="div1">
定宽200px
</div>
<div class="div2">
自适应撑满剩下的空间
</div>
<div class="div3">
定宽200px
</div>
</div>
</body>
</html>