function show_navi(element){
       element.className += "hover";
	document.getElementById("Length").style.visibility = "hidden";
	document.getElementById("adults").style.visibility = "hidden";
   }
 function hide_navi(element){
       element.className = element.className = "";
	document.getElementById("Length").style.visibility = "";
	document.getElementById("adults").style.visibility = "";
     }