jQuery(document).ready(
    function () {
       var nb_random=Math.floor(Math.random()*3)+1;
       jQuery("#boite-entreprise.imgaccueil").css("backgroundImage","url('fileadmin/templates/img/acc-entreprise-"+nb_random+".jpg')");

       nb_random=Math.floor(Math.random()*3)+1;
       jQuery("#boite-services.imgaccueil").css("backgroundImage","url('fileadmin/templates/img/acc-services-"+nb_random+".jpg')");

       nb_random=Math.floor(Math.random()*3)+1;
       jQuery("#boite-carriere.imgaccueil").css("backgroundImage","url('fileadmin/templates/img/acc-carriere-"+nb_random+".jpg')");
    }
);