function setBlend(id_name, trans_num) {
      
      var user_agent = navigator.userAgent;
      if(document.layers) {
          if(trans_num > 0) {
              document.layers[id_name].visibility='visible';
          }
          else if(trans_num==0) {
              document.layers[id_name].visibility='hidden';
          }
      } else if(user_agent.indexOf('Safari')!=-1) {
          
          document.getElementById(id_name).style.Opacity = trans_num;
		  
      } else if(user_agent.indexOf('Mac_PowerPC') !=-1 && document.all) {
          if(trans_num > 0) {
              document.all(id_name).style.visibility='visible';
          }
          else if(trans_num==0) {
              document.all(id_name).style.visibility='hidden';
          }
      } else if(document.all) {
          
          document.getElementById(id_name).style.filter="alpha(opacity=0)";
          document.getElementById(id_name).filters.alpha.opacity  = (trans_num * 100);
          
      } else if(user_agent.indexOf('Gecko')!=-1) {
          
          document.getElementById(id_name).style.MozOpacity = trans_num;
      }
  }