app/views/surveys/preview.html.erb
<%= render 'tabs', survey: survey, selected: :preview %>
<% if survey.not_ready_for_replies? %>
<%= render 'shared/survey_no_questions', survey: survey %>
<% else %>
<div class="d-flex justify-content-center align-items-center pb-3">
<div class="btn-group">
<%= survey_preview_button(title: 'Desktop', width: 1280, height: 800) %>
<%= survey_preview_button(title: 'Tablet', width: 810, height: 1080) %>
<%= survey_preview_button(title: 'Mobile', width: 375, height: 812) %>
</div>
</div>
<iframe
id="preview-frame"
width="1280"
height="800"
class="d-block mx-auto border mt-2"
src="<%= preview_form_path(survey.id) %>">
</iframe>
<% end %>