#bg_off {
    position:fixed;
    top:0px; left:0px;
    width:100%; height:100%;
    _width:expression(eval(document.body.clientWidth));
    _height:expression(eval(document.body.clientHeight));
    _position:absolute;
    _top:expression(eval(document.body.scrollTop));
    filter:alpha(opacity=70); -moz-opacity:0.7; opacity:0.7;
    background:black;
    text-align:center;
}
#dialog {
    position:fixed;
    _position:absolute;
    _top:expression(eval(document.body.scrollTop+(document.body.clientHeight/2))); /* rozmery okna prohlizece: http://www.pixy.cz/blogg/clanky/js-rozmery-okna.html */
    z-index:100;
    top:50%;
    left:50%;
    border:5px solid silver;
    background:white;
    text-align:left;
}
#dialog_close {
    position:absolute;
    top:5px; right:5px;
}