如何清除我的浮動物？

<!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" lang="en-US"> 
<head> 
<style type="text/css"> 
body {width:100%;overflow-x:hidden;} 
*{margin:0; padding:0; border:0;} 
.wrap{float:left;width:100%;background-color:#ccc;} 
.content{width:1000px;margin:0 auto;background-color:#efefef;} 
.left{float:left;width:760px;} 
.right{float:left;width:240px;} 
</style> 
</head> 
<body> 
<div class="wrap"> 
    <div class="content"> 
     <div class="left"> 
      111<br /> 
      222<br /> 
      <!-- there still have some lines --> 
     </div> 
     <div class="right">   
     </div> 
    </div> 
</div> 
</body> 
</html>

DIV高度爲零，背景顏色消失。即使我給DIV.content height auto or 100%。爲什麼背景顏色消失了？如何清除我的浮動物？

來源

2011-02-11 yuli chika

問題是「我怎樣清理我的浮標？」這是*肯定*重複。 – thirtydot 2011-02-11 14:14:27