Wordpress - Remove top admin bar

http://vudu.me/88

Has an article about it.

But basically

/* Disable the Admin Bar. */
add_filter( 'show_admin_bar', '__return_false' );

or also

//REMOVE ADMIN BAR
remove_action('init', 'wp_admin_bar_init');

I believe in your functions.php will disable it. Probably a better way than just hiding it thriough css

THe reason you still get the gap with the menu hidden is because WP adds this css as well

html { margin-top: 28px !important; }
* html body { margin-top: 28px !important; }

So a margin is added up top.... you could negate that css in yours, but just disabling the bar is probably better if that's what you want to do