body, h1, h2, h3, h4, h5, h6, dl, dt, dd, ul, ol, li, th, td, p, blockquote, pre, form, fieldset, legend, input, button, textarea, hr { margin: 0; padding: 0; }
body, input { font: 12px/1.5 Arial; color: #333; }
select, input, button { vertical-align: middle; font-size: 100%; }
ul, ol { list-style: none; }
fieldset, img { border: 0; }
em { font-style: normal; }
.clear { clear: both; }
.clearfix:after { content: "."; display: block; visibility: hidden; clear: both; height: 0; font-size: 0; }
.clearfix { *zoom: 1; }原文：http://www.cnblogs.com/joyfei/p/3650876.html