function changenavtitle(key){
	var spans = document.getElementById("bigSpanNum").getElementsByTagName("SPAN");
	for(var i = 0; i < spans.length; i++){
		var divs = spans[i].getElementsByTagName("DIV");
			if(key == "nav"+i){
				divs[0].className="t_over_BgText";
				divs[1].className="t_over_right";
				document.getElementById("tit2"+i).style.display="block";
				if(i==0){
					document.getElementById("tit21").style.display="none";
//					document.getElementById("ztc").className="ztcText";
					}else{
					var j =i-1;
					var divs1 = spans[j].getElementsByTagName("DIV");
					divs1[1].className="t_over_left";
//					document.getElementById("ztc").className="ztcTextout";
					}
			}else{
				divs[0].className="t_out_BgText";
				divs[1].className="t_out_right";
				document.getElementById("tit2"+i).style.display="none";
			}
		}
		if(key == "nav0"){
			document.getElementById("nav00").className="t_left_over_00";
			document.getElementById("tit20").style.display="none";
		 }else{
			 document.getElementById("nav00").className="t_left_out_00";
			 }
		if(key == "nav7"){
			divs[1].className="t_over_right0"
			}else{
			divs[1].className="t_out_right0"	
			}
			document.getElementById("midBg").style.display="block";
	
}