function ooso (obr, popis, sirka, vyska) {

  sirkaokna = sirka + 100;
  vyskaokna = vyska + 100;
  sirkaobrazovky = screen.width; 
  vyskaobrazovky = screen.height;
  if (vyskaokna + 80 > vyskaobrazovky) vyskaokna = vyskaobrazovky - 80;
  if (sirkaokna + 50 > sirkaobrazovky) sirkaokna = sirkaobrazovky - 50;

  sso  = "<head><title>" + popis + "</title>";
  sso += "</head>\n\n";

  sso += "<body style='background-color: #FFE5BF; padding: 0px; margin: 0px; font-family: Arial CE, Helvetica CE, Arial, Helvetica, sans-serif; font-size: 12px;'>";

  sso += "<img src='" + obr + "' ";
  horniodsazeni = (vyskaokna - vyska) / 2;
  leveodsazeni = (sirkaokna - sirka) / 2;
  sso += "style='position: absolute; top: " + horniodsazeni + "; left: " + leveodsazeni + "; padding: 0px; margin: 0px;' ";
  sso += "width=" + sirka + " height=" + vyska + " onclick='self.close()' ";
  sso += "alt='" + popis + "'>";

  sso += "<h2 style='position: absolute; color: #FF7F00; font-size: 16px; font-weight: bold; width: " + sirkaokna + "px; top: 10px; text-align: center; padding: 0px; margin: 0px;'>";
  sso += popis + "</h2>";

  sso += "<p style='position: absolute; padding: 0px; margin: 0px; width: " + sirkaokna + "px; top: " + (vyskaokna - 20) + "px; text-align: center;'>";
  sso += "Součást webu <a href='../'>www.LevneUbytovani.net</a></p>";

  // kód pro google analytics
  sso += '<script type="text/javascript">';
  sso += 'var gaJsHost = (("https: == document.location.protocol) ? "https://ssl." : "http://www.");';
  sso += 'document.write(unescape("%3Cscript src=\'" + gaJsHost + "google-analytics.com/ga.js\' type=\'text/javascript\'%3E%3C/script%3E"));';
  sso += '</script>';
  sso += '<script type="text/javascript">';
  sso += 'try {';
  sso += 'var pageTracker = _gat._getTracker("UA-7687874-1");';
  sso += 'pageTracker._trackPageview();';
  sso += '} catch(err) {}</script>';
  
  sso += '</body>';

  w = 'width=' + sirkaokna + ',height=' + vyskaokna + ',top=0,left=0,menubar=no,statusbar=no,resizable=yes,scrollbars=no';
  okno = window.open('','',w);

  if (typeof(okno) == false) return false;
  okno.document.open();
  okno.document.write(sso);
  okno.document.close();
  return true;

}