var s=5;
var minheight=85;
var maxheight=165;
function shoppingcat(){
 var content = document.getElementById("content_exper");
 var img1 = content.getElementsByTagName("img")[0];
 var key = document.getElementById("key").innerHTML;
 
 if(key=="展开"){
  content.style.height=content.offsetHeight+s +"px";
  img1.src="images/exper2.jpg";
  if(content.offsetHeight<maxheight){
   setTimeout("shoppingcat();",0);
  }else{
  document.getElementById("key").innerHTML="关闭";
  }
 }else{
  content.style.height=content.offsetHeight-s +"px";
  if(content.offsetHeight>minheight){
   setTimeout("shoppingcat();",0);
  }else{
  img1.src="images/exper1.jpg";
  document.getElementById("key").innerHTML="展开";
  }
 }
}