function show_sub1(){
document.getElementById('top_cards2').style.display='block';
document.getElementById('top_cards2').style.visibility='visible';
document.getElementById('top_cards1').style.display='none';
document.getElementById('top_cards1').style.visibility='hidden';
}
 
function show_sub2(){
document.getElementById('top_cards1').style.display='block';
document.getElementById('top_cards1').style.visibility='visible';
document.getElementById('top_cards2').style.display='none';
document.getElementById('top_cards2').style.visibility='hidden';
}