var star_x = new Array;
	var star_y = new Array;
	var star_s = new Array;

	function rand(n) {
		return Math.floor(n*Math.random())
	}

	function init_stars() {
		var l = document.getElementById('b').offsetLeft;
		var w = document.body.clientWidth;

		for(i=1;i<=2;i++) {
			star_x[i] = rand(l-150);
			star_y[i] = rand(800);
			star_s[i] = rand(50)/100+0.5;
			document.getElementById('star'+i).style.backgroundPosition = star_x[i]+"px "+star_y[i]+"px";
		}

		for(i=3;i<=4;i++) {
			star_x[i] = w-star_x[i-2]-200;
			star_y[i] = rand(800);
			star_s[i] = rand(50)/100+0.5;
			document.getElementById('star'+i).style.backgroundPosition = star_x[i]+"px "+star_y[i]+"px";
		}

	}
	function doevents_stars() {

		for(i=1;i<=4;i++) {
			star_y[i] -= star_s[i];
			document.getElementById('star'+i).style.backgroundPosition = star_x[i]+"px "+star_y[i]+"px";
		}
	}

	init_stars();
	setInterval(doevents_stars, 10);