//画像のプリロード
function PreLoad(obj,val) {
    var d = document;
    var img = obj;
    d.img = new Image();
    d.img.src = val;
}

function show1(){
	top_box1.style.display="block";
	top_box2.style.display="none";
}

function show2(){
	top_box1.style.display="none";
	top_box2.style.display="block";
}