How to select a div in a div which is in active page(div) while using attr event?

How to select a div in a div which is in active page(div) while using attr
event?

I got this:
$(".containers").not(':first').hide();
$("#topbar ul li a").click(function() {
var activeLink = $(this).attr("href");
$("#topbar ul li a").removeClass("active");
$(this).addClass("active");
$(".containers").hide();
$(activeLink).show();
return false;
});
My question here is how can select(call) a div in the active container?
Let's say I am trying to animate box3 as the container3 is clicked or box2
as the container2 is clicked and so on...
You can see it beter here: http://jsfiddle.net/JWBQG/