<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>两列右列宽度自适应</title>
<style>
#left{
border:1px solid #fcc;
height: 200px;
float: left;
width:300px
}
#right{
border :1px solid red;
height: 200px;
}
</style>
</head>
<body>
<div id="left"></div>
<div id="right"></div>
</body>
</html>
