// javascript document
function switchtab(n){  
   for(var i = 1; i <= 3; i++){  
    document.getelementbyid("nav_bt_" + i).classname = "nav_bt_normal";  
	document.getelementbyid("bt_building_text_" + i).classname = "bt_building_text_normal";  
	document.getelementbyid("tab_content_" + i).style.display = "none";  
   }  
   document.getelementbyid("nav_bt_" + n).classname = "nav_bt_active";  
   document.getelementbyid("bt_building_text_" + n).classname = "bt_building_text_active"; 
   document.getelementbyid("tab_content_" + n).style.display = "block";  
   imgchange();
   if(n==1){
	   document.getelementbyid("bt_building_img_1").style.backgroundimage="url(../images/bt_building_active.png)";
	   }else if(n==2){
		   document.getelementbyid("bt_building_img_2").style.backgroundimage="url(../images/bt_real_estate_active.png)";
		   }else if(n==3){
		   document.getelementbyid("bt_building_img_3").style.backgroundimage="url(../images/bt_phar_active.png)";
		   }
 }  
 function imgchange(){ 
	document.getelementbyid("bt_building_img_1").style.backgroundimage="url(../images/bt_building_normal.png)";
	document.getelementbyid("bt_building_img_2").style.backgroundimage="url(../images/bt_real_estate_normal.png)";
	document.getelementbyid("bt_building_img_3").style.backgroundimage="url(../images/bt_phar_normal.png)";
 }