clear元素的margin-top被重置为零
当你使用clear(left & both & right)清理一个浮动元素时,该元素的margin-top会被重置为0。所以为了创建浮动列,并使用footer进行浮动清理时,必须对浮动列(sidebar && content)都指定margin-bottom,最好margin-bottom相同。(Firefox会将margin-top重置0,而IE不重置footer的margin-top)。
例如:
分别在Firefox和IE中运行一下代码,仔细读者会发现页脚(footer)的margin-top在火狐中并没有显示,而在IE中却出现了10像素的上边距。
HTML代码
<body>
<div id="wrapper">
<div id="masthead">
masthead content goes here
</div>
<div id="sidebar">
sidebar content goes here
</div>
<div id="content">
main content goes here
<br/>
main content goes here
</div>
<div id="footer">
footer
</div>
</div>
</body>
CSS代码
<div id="wrapper">
<div id="masthead">
masthead content goes here
</div>
<div id="sidebar">
sidebar content goes here
</div>
<div id="content">
main content goes here
<br/>
main content goes here
</div>
<div id="footer">
footer
</div>
</div>
</body>
body {
margin:0; padding:0;
background-color:#FFFFCC;
}
#wrapper {
width:800px;
margin:0 auto;
}
/*Masthead*/
#masthead {
padding:10px;
background:#FFCC33;
margin-bottom:10px;
}
/*Content*/
#content {
float:left;
width:60%;
background:#CCCCCC;
}
/*Sidebar*/
#sidebar {
float:right;
width:36%;
background:#999999;
}
/*Footer*/
#footer {
clear:both;
padding:10px;
background:#FFCC33;
}
margin:0; padding:0;
background-color:#FFFFCC;
}
#wrapper {
width:800px;
margin:0 auto;
}
/*Masthead*/
#masthead {
padding:10px;
background:#FFCC33;
margin-bottom:10px;
}
/*Content*/
#content {
float:left;
width:60%;
background:#CCCCCC;
}
/*Sidebar*/
#sidebar {
float:right;
width:36%;
background:#999999;
}
/*Footer*/
#footer {
clear:both;
padding:10px;
background:#FFCC33;
}