$(document).ready(function()
{
	//slides the element with class "nav_body" when paragraph with class "nav_head" is clicked 
	$("#firstpane li.nav_head").click(function()
    {
		$(this).css({backgroundImage:"url(down.png)"}).next("div.nav_body").slideToggle(300).siblings("div.nav_body").slideUp("slow");
       	$(this).siblings().css({backgroundImage:"url(left.png)"});
	});
	//slides the element with class "nav_body" when mouse is over the paragraph
	$("#secondpane li.nav_head").mouseover(function()
    {
	     $(this).css({backgroundImage:"url(down.png)"}).next("div.nav_body").slideDown(500).siblings("div.nav_body").slideUp("slow");
         $(this).siblings().css({backgroundImage:"url(left.png)"});
	});
});