How to show Handsome Checkout form first and product description (sidebar) second on mobile screens?

Put the snippet below to the Custom JS field of your Handsome Checkout page:

jQuery(document).ready(function(){

 jQuery('.hide-on-mobile').removeClass('hide-on-mobile');

 jQuery('.hide-on-desktop, .hide-on-tablet').remove();

});

jQuery(document).ready(function(){

jQuery('.hide-on-mobile').removeClass('hide-on-mobile');

jQuery('.hide-on-desktop, .hide-on-tablet').remove();

});