{% extends 'simple_base.html' %}

{% load i18n %}
{% load form_helper %}


{% block body %}
<div class="row">
  <div class="col-lg-8 col-lg-push-2">
    <h2>{% trans "Our Terms of Use have changed" %}</h2>
    {% block terms_details %}{% endblock %}
    <form class="form-horizontal" method="post" action=".?next={{ next }}">
      {% csrf_token %}
      {% if next %}<input type="hidden" name="next" value="{{ next }}"/>{% endif %}
      {% render_form terms_form %}
      <button type="submit" class="btn btn-lg btn-primary">{% trans "Accept" %}</button>
    </form>
  </div>
</div>
{% endblock %}

{% extends 'simple_base.html' %}

{% load i18n %}
{% load form_helper %}


{% block body %}
<div class="row justify-content-md-center mt-5">
  <div class="col-lg-8">
    <h2>{% trans "Our Terms of Use have changed" %}</h2>
    {% block terms_details %}{% endblock %}
    <form class="form-horizontal" method="post" action=".?next={{ next }}">
      {% csrf_token %}
      {% if next %}<input type="hidden" name="next" value="{{ next }}"/>{% endif %}
      {% render_form terms_form %}
      <button type="submit" class="btn btn-lg btn-primary">{% trans "Accept" %}</button>
    </form>
  </div>
</div>
{% endblock %}

Use Bootstrap 4 classes on new terms page
Use Bootstrap 4 classes on new terms page