<div class="xoops-theme-select">
    <form role="form" action="<{xoAppUrl index.php}>" method="post">
        <{$block.theme_select}>
    </form>
</div>
<script>
    $(document).ready(function(){
        $('#xoops_theme_img').css("width","100%").addClass("img-rounded");
    });
</script>