(function(){
            function hoverButtons(){
              var links = document.getElementsByTagName('*'), i = links.length;
              while(i--){
                if(links[i].className.indexOf('boton') != -1){
                  var firstSpan = links[i].getElementsByTagName('span')[0];
                  firstSpan.onmouseover = function(){
                    this.className += ' hover';
                  }
                  firstSpan.onmouseout = function(){
                    this.className = this.className.split(' hover')[0];
                  }
                }
              }
            }
            if(!window.XMLHttpRequest) window.attachEvent('onload', hoverButtons);
        })();