$(document).ready(function(){

// handling topnav hovers
$(".navtd").hover(function () {
$(this,".navtd").css({'background-image' : 'url(images/top21.jpg)', 
'background-repeat': 'repeat-x', 'background-position': 'top'});}, 
function () {$(this,".navtd").css({'background-image' : 'none'});});

$(".navtdas").hover(function () {
$(this,".navtdas").css({'background-image' : 'url(images/top21as.jpg)', 
'background-repeat': 'repeat-x', 'background-position': 'top'});}, 
function () {$(this,".navtdas").css({'background-image' : 'url(images/top2as.jpg)'});});

});