When you go to the WordPress login page and you or a member tries to login but the login fails, a failed box will appear and that box shakes. You can remove the shaking effect by adding the following to your theme’s functions.php file:

function remove_login_shake() { remove_action('login_head', 'wp_shake_js', 12); } 
add_action('login_head', 'remove_login_shake');