function reset_br(){
	var e = document.getElementById("top_menu");
	e.style.backgroundImage="url(img/guziki_1.png)";
}

function zamiana_bg(n){	
	var e = document.getElementById("top_menu");	
	var bg = "../img/guziki_" + n + ".png";
	e.style.backgroundImage='url(' + bg + ')';
}