I am using simple_form in my Rails application, I tried to add form-horizontal class to my form.
<form accept-charset="UTF-8" action="/account/orders" class="simple_form new_order" data-validate="true" enctype="multipart/form-data" id="new_order" method="post" novalidate="novalidate">
When I use html: { class: "form-horizontal" } it change class="simple_form new_order" to class="simple_form form-horizontal".
What should I do to keep new_order class?