wall = new Array();

/* 使用する背景画像を記述 */
wall[0] = "../../shared/images/bg_top0.jpg";
wall[1] = "../../shared/images/bg_top1.jpg";
wall[2] = "../../shared/images/bg_top2.jpg";
wall[3] = "../../shared/images/bg_top3.jpg";
wall[4] = "../../shared/images/bg_top4.jpg";

rnd = Math.round(Math.random() * (wall.length - 1));
document.write('<style type="text/css">#container { background-image:url(' , wall[rnd] , '); background-repeat:no-repeat; background-color:#333;}</style>');