function login(showhide){
    if(showhide == "show"){
        document.getElementById('popupbox').style.visibility="visible"; /* If the function is called with the variable 'show', show the login box */
    }else if(showhide == "hide"){
        document.getElementById('popupbox').style.visibility="hidden"; /* If the function is called with the variable 'hide', hide the login box */
    }
  }