sirka = (window.document.body.clientWidth-100);
  zleva = 0;
  zprava = sirka + 100;

  function kajakJede(Y,krok,rychlost)
   {
    if(zprava > -100)
     {
      document.getElementById('kajakar').style.left = zprava;
      document.getElementById('kajakar').style.display = '';
      document.getElementById('kajakar').style.top = Y;
      zprava=zprava-krok;
      setTimeout("kajakJede("+Y+","+krok+","+rychlost+")",rychlost);
     }
     else
     {
      document.getElementById('kajakar').style.display = 'none';
      zleva = -100;
      zprava = sirka+100;
      kajakJedeZpet(Math.round(Math.random()*400+50),2,10);
     }
   }

  function kajakJedeZpet(Y,krok,rychlost)
   {
    if(zleva < sirka + 100)
     {
      document.getElementById('kajakar-zpet').style.left = zleva;
      document.getElementById('kajakar-zpet').style.display = '';
      document.getElementById('kajakar-zpet').style.top = Y;
      zleva=zleva+krok;
      setTimeout("kajakJedeZpet("+Y+","+krok+","+rychlost+")",rychlost);
     }
     else
     {
      document.getElementById('kajakar-zpet').style.display = 'none';
      zleva = - 100;
      zprava = sirka + 100;
      kajakJede(Math.round(Math.random()*400+50),2,10);
     }
   }

  kajakJede(Math.round(Math.random()*400+50),2,10);