function expandbanner(){
  this.floatBan=document.getElementById("floatBan");
  this.floatBan.style.width = '200px';
  this.floatBan.style.height= '250px';
  this.floatBan.style.overflow= "hidden";
}

function contractbanner(){
  this.floatBan=document.getElementById("floatBan");
  this.floatBan.style.width = '1px';
  this.floatBan.style.height= '1px';
  this.floatBan.style.overflow= "hidden";
}

function contractbanner_bf(){
  this.floatBan=document.getElementById("floatBan_bf");
  this.floatBan.style.width = '1px';
  this.floatBan.style.height= '1px';
  this.floatBan.style.overflow= "hidden";
}