topnav = function() {     

   var sfEls = document.getElementById("topnav").getElementsByTagName("LI");
   for (var i=0; i<sfEls.length; i++) {

      sfEls[i].onmouseover=function() {
         this.className+=" sfhover";
      }
      sfEls[i].onmouseout=function() {
         this.className=this.className.replace(new RegExp(" sfhover\\b"), "");
      }

   }
   
}

sidenav = function() {     

   var sfEls = document.getElementById("sidenav").getElementsByTagName("LI");
   for (var i=0; i<sfEls.length; i++) {

      sfEls[i].onmouseover=function() {
         this.className+=" sfhover";
      }
      sfEls[i].onmouseout=function() {
         this.className=this.className.replace(new RegExp(" sfhover\\b"), "");
      }

   }

}

if (window.attachEvent) window.attachEvent("onload", topnav); 
if (window.attachEvent) window.attachEvent("onload", sidenav);