banner_images = Array(
   '/elements/img/boys_banner.jpg',
   '/elements/img/boys2_banner.jpg',
   '/elements/img/class_banner.jpg',
   '/elements/img/farm_banner.jpg',
   '/elements/img/girl_banner.jpg',
   '/elements/img/mt_1_banner.jpg',
   '/elements/img/silo2_banner.jpg'
   );
banner_length = banner_images.length;
random_index = Math.round((banner_length-1) * Math.random())
banner = banner_images[random_index];

$(document).ready(function () {
   $("div#hd").css("background", "transparent url('" + banner + "') no-repeat top right");
});