// ランダムに背景画像を変更する
img = new Array();
img[0] = "index_img/header00.jpg";
img[1] = "index_img/header01.jpg";
img[2] = "index_img/header02.jpg";
img[3] = "index_img/header03.jpg";
img[4] = "index_img/header04.jpg";
img[5] = "index_img/header05.jpg";
img[6] = "index_img/header06.jpg";
img[7] = "index_img/header07.jpg";
img[8] = "index_img/header08.jpg";
img[9] = "index_img/header09.jpg";
n = Math.floor(Math.random()*img.length);
document.write("<img src='"+img[n]+"' border='0'>");