Available placeholders can be found here:
https://wp-events-plugin.com/documentation/placeholders/
(Page is also in the help section of the plugin.)
To make the booking form responsive you need to style it in your own css stylesheet, so it suits your theme and design. ??
Here’s a starter:
function my_em_event_booking_form_responsive_css(){
?>
<style type="text/css">
div.em-booking-form-details { float: none; width:auto; }
div.em-booking-form-details p label { float:none; width:auto; display:block; }
div.em-booking-form-details input[type="text"], div.em-booking-form-details select, div.em-booking-form-details textarea { width:99%; padding:1%; }
div.em-booking-login { float:none; margin:0px !important; border:0px !important; }
div.em-booking div.em-booking-login { display:none; }
</style>
<?php
}
add_action('wp_head', 'my_em_event_booking_form_responsive_css');
It’s not a good idea to embed it in the template file, because then you lose all conditions that EM automatically attaches to the booking form, like booking end date etc.
Much better to use the Formatting section in the settings.