if (screen.width < 1000)
    {
         document.write('<img src="images/main/fon-nadpis.png" alt="" class="header_img" />');
    }
    else
        if (screen.width > 1000)
            {
                document.write('<img src="images/main/fon-nadpis.png" alt="" class="header_img" />');
                document.write('<img src="images/main/karatist.png" alt="" align="right" border="0" style="float:right" />');
            }