清除Html元素浮动

html body div.clear,
html body span.clear
{
     background: none;
     border: 0;
     clear: both;
     display: block;
     float: none;
     font-size: 0;
     margin: 0;
     padding: 0;
     overflow: hidden;
     visibility: hidden;
     width: 0;
     height: 0;
}