wall = new Array();

/* 使用する背景画像を好きなだけ記述 */
wall[0] = "./image/share/bg01.jpg";
wall[1] = "./image/share/bg02.jpg";
wall[2] = "./image/share/bg03.jpg";
wall[3] = "./image/share/bg04.jpg";
wall[4] = "./image/share/bg05.jpg";
wall[5] = "./image/share/bg06.jpg";
wall[6] = "./image/share/bg07.jpg";
wall[7] = "./image/share/bg08.jpg";
wall[8] = "./image/share/bg09.jpg";
wall[9] = "./image/share/bg10.jpg";

rnd = Math.round(Math.random() * (wall.length - 1));
document.write('<style type="text/css">.MainImg { background-image:url(' , wall[rnd] , '); border-top: 3px solid #ff7200; background-repeat: no-repeat; background-position: center top; text-align: center;}</style>');