symposion_app/pinaxcon/templates/symposion/schedule/_slot_edit.html

{% load i18n bootstrap %}
<div class="modal-dialog modal-dialog-centered" role="document">
  <div class="modal-content">
    <div class="modal-header">
      <h5 class="modal-title">{% trans "Edit Slot" %}</h5>
      <button type="button" class="close" data-dismiss="modal" aria-label="Close">
        <span aria-hidden="true">&times;</span>
      </button>
    </div>

    <div class="modal-body">
      <form class="form-horizontal" id="slotEditForm" class="modal-form" method="POST" action="{% url "schedule_slot_edit" slug slot.pk %}">
        {% csrf_token %}
        {{ form|bootstrap }}
      </form>
    </div>

    <div class="modal-footer">
      <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
      <button type="submit" class="btn btn-primary">Save changes</button>
    </div>
</div>