function focusclear( thisfield ) {
    if ((thisfield.name == "site_login") && (thisfield.value == "login")){
      thisfield.value = "";
    }
    if ((thisfield.name == "site_pass") && (thisfield.value == "pass")){
      thisfield.value = "";
    }
  }

  function checkform ( form )
  {

    if (form.site_login.value == "") {
      alert( "Nie wprowadzono identyfikatora użytkownika!" );
      form.site_login.focus();
      return false ;
    }
    if (form.site_pass.value == "") {
      alert( "Nie wprowadzono hasła!" );
      form.site_pass.focus();
      return false ;
    }
    return true ;
  }