var no = 10;			// pocet vlocek
var speed = 25;		// mensi cislo = rychlejsi pohyb vlocek
var snowflake = "deset.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 = 970, doc_height = 650;

if (ns4up) {
	doc_width = self.innerWidth;
	doc_height = self.innerHeight;
} else if (ie4up) {
	//doc_width = 500;
	//doc_height = 500;
}

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 = 1000; i < no + 1000; ++ 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();
}