浮动引发的Bug
浮动的方法
float：left；right；none
浮动的原理
改变元素的排布方式；浮动元素会脱离文档流。
浮动影响
产生卡顿；浮动的子元素撑不开父元素高度。父元素不设置高度，子元素都浮动；
浮动解决方法
1.给父级也加浮动（这种情况当父级margin:0 auto;时不居中）
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>1.给父级也加浮动(不居中了)</title>
<style>
.parentElement{ width:300px;margin:0 auto;border:10px solid #000;float:left;}
.subElement{ width:200px;height:200px;background:red;float:left;}
</style>
</head>
<body>
<div class="parentElement">
<div class="subElement"></div>
</div>
</body>
</html>
2.给父级加display:inline-block;(这种情况当父级margin:0 auto;时不居中。只有IE6,7居中)
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>给父级加display:inline-block</title>
<style>
.parentElement{ width:300px;margin:0 auto;border:10px solid #000; display:inline-block;}
.subElement{ width:200px;height:200px;background:red;float:left;}
</style>
</head>
<body>
<div class="parentElement">
<div class="subElement"></div>
</div>
</body>
</html>
3.在浮动元素下加
IE6下，块元素有最小高度，即当height<19px时，默认为19px;
解决方法：font-size:0;或overflow:hidden;
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>在浮动元素下加<div class="clear"></div></title>
<style>
.parentElement{ width:300px;margin:0 auto;border:10px solid #000;}
.subElement{ width:200px;height:200px;background:red;float:left;}
.clear{ height:0px;font-size:0;clear:both;}
</style>
</head>
<body>
<div class="parentElement">
<div class="subElement"></div>
<div class="clear"></div>
</div>
</body>
</html>
4.在浮动元素下加
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>在浮动元素下加<br clear="all"/></title>
<style>
.parentElement{ width:300px;margin:0 auto;border:10px solid #000;}
.subElement{ width:200px;height:200px;background:red;float:left;}
</style>
</head>
<body>
<div class="parentElement">
<div class="subElement"></div>
<br clear="all"/>
</div>
</body>
</html>
5.给浮动元素父级加{zoom:1;}
:after{content:""; display:block;clear:both;}
在IE6，7下浮动元素的父级有宽度就不用清浮动
haslayout 根据元素内容的大小 或者父级的父级的大小来重新的计算元素的宽高
display: inline-block
height: (任何值除了auto)
float: (left 或 right)
width: (任何值除了auto)
zoom: (除 normal 外任意值)
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<style>
.parentElement{margin:0 auto;border:10px solid #000;}
.subElement{ width:200px;height:200px;background:red;float:left;}
.clear{zoom:1;}
.clear:after{content:""; display:block;clear:both;}
</style>
</head>
<body>
<div class="parentElement clear">
<div class="subElement"></div>
</div>
</body>
</html>
6.给浮动元素父级加overflow:auto;或者overflow:hidden;
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>无标题文档</title>
<style>
.parentElement{ width:300px;border:10px solid #000;overflow:hidden;}
.subElement{ width:200px;height:200px;background:Red;float:left;}
</style>
</head>
<body>
<div class="parentElement">
<div class="subElement"></div>
</div>
</body>
</html>
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