snevejr på hp stopper ved halvdelen af siden

hvorfor stopper mit snevejr på halvdelen af siden?? kan ik ik køre hele vejen ned??
http://yellowside.dk/jul.html <-- prøv og se


her er scriptet jeg har brugt (fra http://www.html.dk/scripts/javascript/00022/):

<script LANGUAGE="JavaScript1.2">
<!-- Original:  Altan (snow@altan.hr) -->
<!-- Web Site:  http://www.altan.hr/snow -->

<!-- Begin
var no = 20; // snow number
var speed = 7; // smaller number moves the snow faster
var snowflake = "knap/sne11.gif";

var ns4up = (document.layers) ? 1 : 0;  // browser sniffer
var ie4up = (document.all) ? 1 : 0;
var dx, xp, yp;    // coordinate and position variables
var am, stx, sty;  // amplitude and step variables
var i, doc_width = 800, doc_height = 600;
if (ns4up) {
  doc_width = self.innerWidth;
  doc_height = self.innerHeight;
} else if (ie4up) {
  doc_width = document.body.clientWidth;
  doc_height = document.body.clientHeight;
}
dx = new Array();
xp = new Array();
yp = new Array();
am = new Array();
stx = new Array();
sty = new Array();
for (i = 0; i < no; ++ i) {
dx[i] = 0;                        // set coordinate variables
xp[i] = Math.random()*(doc_width-50);  // set position variables
yp[i] = Math.random()*doc_height;
am[i] = Math.random()*20;        // set amplitude variables
stx[i] = 0.02 + Math.random()/10; // set step variables
sty[i] = 0.7 + Math.random();    // set step variables
if (ns4up) {                      // set layers
  if (i == 0) {
    document.write("<layer name=\"dot"+ i +"\" left=\"15\" ");
    document.write("top=\"15\" visibility=\"show\"><img src=\"");
    document.write(snowflake + "\" border=\"0\"></layer>");
  } else {
    document.write("<layer name=\"dot"+ i +"\" left=\"15\" ");
    document.write("top=\"15\" visibility=\"show\"><img src=\"");
    document.write(snowflake + "\" border=\"0\"></layer>");
  }
} else if (ie4up) {
  if (i == 0) {
    document.write("<div id=\"dot"+ i +"\" style=\"POSITION: ");
    document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");
    document.write("visible; TOP: 15px; LEFT: 15px;\"><img src=\"");
    document.write(snowflake + "\" border=\"0\"></div>");
} else {
    document.write("<div id=\"dot"+ i +"\" style=\"POSITION: ");
    document.write("absolute; Z-INDEX: "+ i +"; VISIBILITY: ");
    document.write("visible; TOP: 15px; LEFT: 15px;\"><img src=\"");
    document.write(snowflake + "\" border=\"0\"></div>");
}
}
}
function snowNS() {  // Netscape main animation function
for (i = 0; i < no; ++ i) {  // iterate for every dot
yp[i] += sty[i];
if (yp[i] > doc_height-50) {
  xp[i] = Math.random()*(doc_width-am[i]-30);
  yp[i] = 0;
  stx[i] = 0.02 + Math.random()/10;
  sty[i] = 0.7 + Math.random();
  doc_width = self.innerWidth;
  doc_height = self.innerHeight;
}
dx[i] += stx[i];
document.layers["dot"+i].top = yp[i];
document.layers["dot"+i].left = xp[i] + am[i]*Math.sin(dx[i]);
}
setTimeout("snowNS()", speed);
}
function snowIE() {  // IE main animation function
for (i = 0; i < no; ++ i) {  // iterate for every dot
yp[i] += sty[i];
if (yp[i] > doc_height-50) {
  xp[i] = Math.random()*(doc_width-am[i]-30);
  yp[i] = 0;
  stx[i] = 0.02 + Math.random()/10;
  sty[i] = 0.7 + Math.random();
  doc_width = document.body.clientWidth;
  doc_height = document.body.clientHeight;
}
dx[i] += stx[i];
document.all["dot"+i].style.pixelTop = yp[i];
document.all["dot"+i].style.pixelLeft = xp[i] + am[i]*Math.sin(dx[i]);
}
setTimeout("snowIE()", speed);
}
if (ns4up) {
  snowNS();
} else if (ie4up) {
  snowIE();
}
// End -->
</script>