Nathan Allen

Yeah, it really should be included in their documentation. It would certainly save everyone a whole lot of time. At least this page will be useful for anyone searching for a solution.

The styles are added using wp_enqueue_style in plugins/all-in-one-event-calendar/app/controller/class-ai1ec-calendar-controller.php near line 543.

So I think the best option is to work out which files you want to edit, then copy them to your theme directory and add some extra code to your functions.php to replace the default css with the modified css. For example, in my functions.php I have:

function replace_calendar_styles() {
wp_dequeue_style('ai1ec-general');
wp_dequeue_style('ai1ec-calendar');
$path = get_stylesheet_directory_uri();
wp_register_style('custom-ai1ec-general', $path.'/general.css');
wp_register_style('custom-ai1ec-calendar', $path.'/calendar.css');
wp_enqueue_style( 'custom-ai1ec-general');
wp_enqueue_style( 'custom-ai1ec-calendar');
}
add_action('wp_print_styles', 'replace_calendar_styles');