求帮忙看有什么问题
right部分背景不显示
<!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 http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
#mid_content{width:1200px;height:800px;margin:0 auto;}
#mid_left{width:33%;float:left;height:400px;background:green};
#mid_right{width:34%;float:right;height:400px;background:yellow;}
</style>
</head>
<body>
<div id="mid_content">
<div id="mid_left">left</div>
<div id="mid_left">left</div>
<div id="mid_right">rightrightrightright</div>
</div>
</body>
</html>
