//preload btns
var btns=new Array("topmenu/btnkontakt.gif","topmenu/btnanfahrt.gif","topmenu/btnoffen.gif");

var btnimg = new Array();
var btnimgover = new Array();

for(var i=0;i<btns.length;i++) {
	btnimg[i]=new Image();
	btnimgover[i]=new Image();
	
	punkt=btns[i].lastIndexOf('.');
	ext=btns[i].substring(punkt);
	
	btnimg[i].src="img/"+btns[i];
	btnimgover[i].src="img/"+btns[i].substring(0,punkt)+"o"+ext;
}

function btnhi(nr) {
	//mouseover
	document.images["btn"+nr].src=btnimgover[nr-1].src;
}

function btnlow(nr) {
	//mouseout
	document.images["btn"+nr].src=btnimg[nr-1].src;
}