I have created my own theme in drupal 7 using only
page.tpl.php as I am happy to use the same template for every node/page.
When visiting mysite.com/?q=user/login every sidebar-navbar from my theme appears there as expected and I would like to remove them from the login form though I really want to avoid creating the login template page--user--login.tpl.php. I was thinking of using the default body class somehow
<body class="html not-front not-logged-in no-sidebars page-user page-user-login">
<body class="maintenance-page in-maintenance no-sidebars">