From http://net.tutsplus.com/tutorials/html-css-techniques/the-30-css-selectors-you-must-memorize/

clearfix.css

.clearfix:after {
    content: "";
    display: block;
    clear: both;
    visibility: hidden;
    font-size: 0;
    height: 0;
    }

.clearfix { 
   *display: inline-block; 
   _height: 1%;
}