著名的万能float闭合

/*说明: 需要注意的就是#main的padding值、footer的高度和负margin值，需要保持一致。下面是著名的万能float闭合Clearfix Hack*/
.clearfix:after {
content: ".";
display: block;
height: 0;
clear: both;
visibility: hidden;}
.clearfix {display: inline-block;}
/* Hides from IE-mac \*/
* html .clearfix { height: 1%;}
.clearfix {display: block;}
/* End hide from IE-mac */