var bgc = new Array();
    bgc[0] = "/wp/img/visual/01.jpg";
    bgc[1] = "/wp/img/visual/02.jpg";
    bgc[2] = "/wp/img/visual/03.jpg";
    bgc[3] = "/wp/img/visual/04.jpg";
    bgc[4] = "/wp/img/visual/05.jpg";
    bgc[5] = "/wp/img/visual/06.jpg";
    bgc[6] = "/wp/img/visual/07.jpg";
var hio = Math.floor(bgc.length*Math.random());
bgc = bgc[Math.floor(hio)];
document.write('<style type="text/css"><!--body {background:#F5F4F1 url("'+ bgc +'") top center no-repeat;}--></style>');